The Enzyme Database

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EC 4.2.1.178     
Accepted name: difructose-dianhydride-III synthase
Reaction: inulobiose = α-D-fructofuranose-β-D-fructofuranose 2′,1:2,3′-dianhydride + H2O
Glossary: difructose anhydride III = α-D-fructofuranose-β-D-fructofuranose 2′,1:2,3′-dianhydride
inulobiose = β-D-fructofuranosyl-(2→1)-D-fructose
Other name(s): DFA-IIIase; difructose anhydride III hydrolase
Systematic name: inulobiose hydro-lyase (α-D-fructofuranose-β-D-fructofuranose 2′,1:2,3′-dianhydride-forming)
Comments: The enzyme participates in an inulin degradation pathway, in which it forms inulobiose from difructose anhydride III. A conformational change in the enzyme from the bacterium Pseudarthrobacter chlorophenolicus results in it also catalysing the activity of EC 4.2.2.18, inulin fructotransferase (DFA-III-forming).
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Tanaka, T., Uchiyama, T., Kobori, H. and Tanaka, K. Enzymic hydrolysis of di-D-fructofuranose 1, 2′; 2, 3′ dianhydride with Arthrobacter ureafaciens. J. Biochem. 78 (1975) 1201–1206. [DOI] [PMID: 1225919]
2.  Neubauer, A., Walter, M., and Buchholz, K. Formation of inulobiose from difructoseanhydride III catalysed by a lysate from Arthrobacter ureafaciens ATCC 21124. Biocatalysis and Biotransformation 18 (2000) 443–455. [DOI]
3.  Saito, K., Sumita, Y., Nagasaka, Y., Tomita, F. and Yokota, A. Molecular cloning of the gene encoding the di-D-fructofuranose 1,2′:2,3′ dianhydride hydrolysis enzyme (DFA IIIase) from Arthrobacter sp. H65-7. J. Biosci. Bioeng. 95 (2003) 538–540. [DOI] [PMID: 16233453]
4.  Yu, S., Wang, X., Zhang, T., Stressler, T., Fischer, L., Jiang, B. and Mu, W. Identification of a novel di-D-fructofuranose 1,2′:2,3′ dianhydride (DFA III) hydrolysis enzyme from Arthrobacter aurescens SK8.001. PLoS One 10:e0142640 (2015). [DOI] [PMID: 26555784]
5.  Yu, S., Shen, H., Cheng, Y., Zhu, Y., Li, X., and Mu, W. Structural and functional basis of difructose anhydride III hydrolase, which sequentially converts inulin using the same catalytic residue. ACS Catalysis 8 (2018) 10683–10697. [DOI]
[EC 4.2.1.178 created 2021]
 
 
EC 4.2.1.179     
Accepted name: difructose-anhydride-I synthase
Reaction: inulobiose = bis-D-fructose 2′,1:2,1′-dianhydride + H2O
Glossary: α-D-fructofuranose-β-D-fructofuranose 2′,1:2,1′-dianhydride = bis-D-fructose 2′,1:2,1′-dianhydride = difructose anhydride I = DFA-I
Other name(s): DFAIase; inulobiose hydrolase; bis-D-fructose 2′,1:2,1′-dianhydride fructohydrolase
Systematic name: inulobiose hydro-lyase (α-D-fructofuranose-β-D-fructofuranose 2′,1:2,1′-dianhydride-forming)
Comments: The enzyme, studied in the fungus Aspergillus fumigatus, may participate in an inulin degradation pathway in which it converts the product of EC 4.2.2.17, inulin fructotransferase (DFA-I-forming), to inulobiose, though in vitro activity was higher in the direction of DFA-I formation.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 121479-55-8
References:
1.  Matsuyama, T. and Tanaka, K. On the enzyme of Aspergillus fumigatus producing difructose anhydride I from inulobiose. Agric. Biol. Chem. 53 (1989) 831–832.
2.  Matsuyama, T., Tanaka, K., Mashiko, M. and Kanamoto, M. Enzymic formation of di-D-fructose 1,2′; 2,1′ dianhydride from inulobiose by Aspergillus fumigatus. J. Biochem. (Tokyo) 92 (1982) 1325–1328. [PMID: 6757245]
[EC 4.2.1.179 created 1992 as EC 3.2.1.134, transferred to EC 4.2.1.179 2021]
 
 
EC 4.2.1.180     
Accepted name: (E)-benzylidenesuccinyl-CoA hydratase
Reaction: (R,S)-2-(α-hydroxybenzyl)succinyl-CoA = (E)-benzylidenesuccinyl-CoA + H2O
Other name(s): bbsH (gene name)
Systematic name: (R,S)-2-(α-hydroxybenzyl)succinyl-CoA hydro-lyase
Comments: The enzyme, purified from the bacterium Thauera aromatica, is involved in an anaerobic toluene degradation pathway in which it catalyses the hydration of (E)-benzylidenesuccinyl-CoA.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  von Horsten, S., Lippert, M.L., Geisselbrecht, Y., Schuhle, K., Schall, I., Essen, L.O. and Heider, J. Inactive pseudoenzyme subunits in heterotetrameric BbsCD, a novel short-chain alcohol dehydrogenase involved in anaerobic toluene degradation. FEBS J. (2021) . [DOI] [PMID: 34601806]
[EC 4.2.1.180 created 2022]
 
 
EC 4.2.1.181     
Accepted name: 3-carboxymethyl-3-hydroxy-acyl-[acp] dehydratase
Reaction: a 3-carboxymethyl-3-hydroxy-acyl-[acyl-carrier protein] = a 4-carboxy-3-alkylbut-2-enoyl-[acyl-carrier protein] + H2O
Other name(s): aprF (gene name); corF (gene name); curE (gene name); pedL (gene name); 3-carboxymethyl-3-hydroxy-acyl-[acyl-carrier protein] dehydratase
Systematic name: 3-carboxymethyl-3-hydroxy-acyl-[acyl-carrier protein] hydro-lyase
Comments: This family of enzymes participates in a process that introduces a methyl branch into nascent polyketide products. The process begins with EC 4.1.1.124, malonyl-[acp] decarboxylase, which converts the common extender unit malonyl-[acp] to acetyl-[acp]. The enzyme is a mutated form of a ketosynthase enzyme, in which a Cys residue in the active site is modified to a Ser residue, leaving the decarboxylase function intact, but nulifying the ability of the enzyme to form a carbon-carbon bond. Next, EC 2.3.3.22, 3-carboxymethyl-3-hydroxy-acyl-[acp] synthase, utilizes the acetyl group to introduce the branch at the β position of 3-oxoacyl intermediates attached to a polyketide synthase, forming a 3-hydroxy-3-carboxymethyl intermediate. This is followed by dehydration catalysed by EC 4.2.1.181, 3-carboxymethyl-3-hydroxy-acyl-[acp] dehydratase (often referred to as an ECH1 domain), leaving a 3-carboxymethyl group and forming a double bond between the α and β carbons. The process concludes with decarboxylation catalysed by EC 4.1.1.125, 4-carboxy-3-alkylbut-2-enoyl-[acp] decarboxylase (often referred to as an ECH2 domain), leaving a methyl branch at the β carbon. The enzymes are usually encoded by a cluster of genes referred to as an "HMGS cassette", based on the similarity of the key enzyme to EC 2.3.3.10, hydroxymethylglutaryl-CoA synthase. cf. EC 4.2.1.18, methylglutaconyl-CoA hydratase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Gu, L., Jia, J., Liu, H., Hakansson, K., Gerwick, W.H. and Sherman, D.H. Metabolic coupling of dehydration and decarboxylation in the curacin A pathway: functional identification of a mechanistically diverse enzyme pair. J. Am. Chem. Soc. 128 (2006) 9014–9015. [DOI] [PMID: 16834357]
2.  Gu, L., Wang, B., Kulkarni, A., Geders, T.W., Grindberg, R.V., Gerwick, L., Hakansson, K., Wipf, P., Smith, J.L., Gerwick, W.H. and Sherman, D.H. Metamorphic enzyme assembly in polyketide diversification. Nature 459 (2009) 731–735. [DOI] [PMID: 19494914]
3.  Erol, O., Schaberle, T.F., Schmitz, A., Rachid, S., Gurgui, C., El Omari, M., Lohr, F., Kehraus, S., Piel, J., Muller, R. and Konig, G.M. Biosynthesis of the myxobacterial antibiotic corallopyronin A. Chembiochem 11 (2010) 1253–1265. [DOI] [PMID: 20503218]
4.  Grindberg, R.V., Ishoey, T., Brinza, D., Esquenazi, E., Coates, R.C., Liu, W.T., Gerwick, L., Dorrestein, P.C., Pevzner, P., Lasken, R. and Gerwick, W.H. Single cell genome amplification accelerates identification of the apratoxin biosynthetic pathway from a complex microbial assemblage. PLoS One 6:e18565 (2011). [DOI] [PMID: 21533272]
[EC 4.2.1.181 created 2023]
 
 
EC 4.2.1.182     
Accepted name: phosphomevalonate dehydratase
Reaction: (R)-5-phosphomevalonate = (2E)-3-methyl-5-phosphooxypent-2-enoate + H2O
Glossary: (2E)-3-methyl-5-phosphooxypent-2-enoate = trans-anhydromevalonate 5-phosphate
Systematic name: (R)-5-phosphomevalonate hydro-lyase
Comments: The enzyme catalyses a step in an archaeal prenyl diphosphate biosynthesis pathway. It belongs to the aconitase X family, and contains a [4Fe-4S] cluster.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Hayakawa, H., Motoyama, K., Sobue, F., Ito, T., Kawaide, H., Yoshimura, T. and Hemmi, H. Modified mevalonate pathway of the archaeon Aeropyrum pernix proceeds via trans-anhydromevalonate 5-phosphate. Proc. Natl. Acad. Sci. USA 115 (2018) 10034–10039. [DOI] [PMID: 30224495]
2.  Yoshida, R., Yoshimura, T. and Hemmi, H. Reconstruction of the "archaeal" mevalonate pathway from the methanogenic archaeon Methanosarcina mazei in Escherichia coli cells. Appl. Environ. Microbiol. 86:e02889-19 (2020). [DOI] [PMID: 31924615]
3.  Komeyama, M., Kanno, K., Mino, H., Yasuno, Y., Shinada, T., Ito, T. and Hemmi, H. A [4Fe-4S] cluster resides at the active center of phosphomevalonate dehydratase, a key enzyme in the archaeal modified mevalonate pathway. Front Microbiol. 14:1150353 (2023). [DOI] [PMID: 36992929]
[EC 4.2.1.182 created 2023]
 
 
EC 4.2.1.183     
Accepted name: etheroleic acid synthase
Reaction: (9Z,11E,13S)-13-hydroperoxy-9,11-octadecadienoate = (9Z,11E)-12-[(1E)-hex-1-en-1-yloxy]dodeca-9,11-dienoate + H2O
Glossary: (9Z,11E)-12-[(1E)-hex-1-en-1-yloxy]dodeca-9,11-dienoic acid = etheroleic acid
(9Z,11E,13S)-13-hydroperoxy-9,11-octadecadienoic acid = 13(S)-HPOD
Other name(s): colneleic acid/etheroleic acid synthase; 13/9-DES; 9/13-DES; 13/9-divinyl ether synthase; (9Z,11E)-12-[(1E)-hex-1-en-1-yloxy]dodeca-9,11-dienoate synthase
Systematic name: (9Z,11E,13S)-13-hydroperoxy-9,11-octadecadienoate lyase
Comments: A heme-thiolate protein (P-450) occurring in several plants, including Allium sativum (garlic) and Selaginella moellendorffii (spikemoss). The enzyme also catalyses the reaction of EC 4.2.1.121, colneleate synthase, to a lesser extent.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Grechkin, A.N., Fazliev, F.N. and Mukhtarova, L.S. The lipoxygenase pathway in garlic (Allium sativum L.) bulbs: detection of the novel divinyl ether oxylipins. FEBS Lett. 371 (1995) 159–162. [DOI] [PMID: 7672118]
2.  Stumpe, M., Carsjens, J.G., Gobel, C. and Feussner, I. Divinyl ether synthesis in garlic bulbs. J. Exp. Bot. 59 (2008) 907–915. [DOI] [PMID: 18326559]
3.  Gorina, S.S., Toporkova, Y.Y., Mukhtarova, L.S., Smirnova, E.O., Chechetkin, I.R., Khairutdinov, B.I., Gogolev, Y.V. and Grechkin, A.N. Oxylipin biosynthesis in spikemoss Selaginella moellendorffii: Molecular cloning and identification of divinyl ether synthases CYP74M1 and CYP74M3. Biochim. Biophys Acta 1861 (2016) 301–309. [DOI] [PMID: 26776054]
[EC 4.2.1.183 created 2024]
 
 
EC 4.2.1.184     
Accepted name: (3S)-3-hydroxy-D-aspartate dehydratase
Reaction: (3S)-3-hydroxy-D-aspartate = 2-iminosuccinate + H2O
Other name(s): bhcB (gene name)
Systematic name: (3S)-3-hydroxy-D-aspartate hydro-lyase
Comments: The enzyme, characterized from the bacterium Paracoccus denitrificans, participates in the the β-hydroxyaspartate cycle of glyoxylate assimilation.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Schada von Borzyskowski, L., Severi, F., Kruger, K., Hermann, L., Gilardet, A., Sippel, F., Pommerenke, B., Claus, P., Cortina, N.S., Glatter, T., Zauner, S., Zarzycki, J., Fuchs, B.M., Bremer, E., Maier, U.G., Amann, R.I. and Erb, T.J. Marine Proteobacteria metabolize glycolate via the β-hydroxyaspartate cycle. Nature 575 (2019) 500–504. [DOI] [PMID: 31723261]
[EC 4.2.1.184 created 2025]
 
 
EC 4.2.1.185     
Accepted name: 6-deoxy-6-sulfo-D-galactonate dehydratase
Reaction: 6-deoxy-6-sulfo-D-galactonate = 2-dehydro-3,6-dideoxy-6-sulfo-D-galactonate + H2O
Glossary: 6-deoxy-6-sulfo-D-galactonate = sulfogalactonate
Other name(s): sulfogalactonate dehydratase; SfcF
Systematic name: 6-deoxy-6-sulfo-D-galactonate hydro-lyase (2-dehydro-3,6-dideoxy-6-sulfo-D-galactonate forming)
Comments: This enzyme, characterized from the bacterium Paracoccus wurundjeri strain Merri, participates in a sulfofucose degradation pathway. cf. EC 4.2.1.162, 6-deoxy-6-sulfo-D-gluconate dehydratase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Stewart, A.WE., Li, J., Lee, M., Lewis, J.M., Herisse, M., Hofferek, V., McConville, M.J., Pidot, S.J., Scott, N.E. and Williams, S.J. Tandem sulfofucolytic-sulfolactate sulfolyase pathway for catabolism of the rare sulfosugar sulfofucose. mBio 16:e0184025 (2025). [DOI] [PMID: 40823846]
[EC 4.2.1.185 created 2025]
 
 
EC 4.2.1.186     
Accepted name: 3-cyano-L-homoalanine synthase
Reaction: ATP + L-glutamine = AMP + diphosphate + 2-amino-4-cyanobutanoate (overall reaction)
(1a) ATP + H2O = AMP + diphosphate
(1b) L-glutamine + AMP = (2S)-5-[(5′-adenylyl)oxy]-5-imino-2-aminopentanoate + H2O
(1c) (2S)-5-[(5′-adenylyl)oxy]-5-imino-2-aminopentanoate = 2-amino-4-cyanobutanoate + AMP
Glossary: 2-amino-4-cyanobutanoate = 3-cyano-L-homoalanine = L-γ-cyanohomoalanine
Other name(s): nitB (gene name); artA (gene name)
Systematic name: L-glutamine hydro-lyase (ATP-hydrolysing, 3-cyano-L-homoalanine-forming)
Comments: The enzyme, charaterized from the fungi Penicillium aurantiocandidum and Aspergillus lentulus, participates in the biosynthesis of the the fungal antimicrobial compound auranthine. It is a member of a family of argininosuccinate synthetase (EC 6.3.4.5)-like nitrile synthases that are widespread in fungi and bacteria. Note that while a water molecule is released from L-glutamine, another one is incorporated during the hydrolysis of ATP, and thus the overall reaction does not include water.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Kishimoto, S., Tamura, T., Okamoto, T. and Watanabe, K. Enantioselective biosynthesis of (+)- and (–)-auranthines. J. Am. Chem. Soc. 147 (2025) 10612–10617. [DOI] [PMID: 40099513]
2.  Zeng, Y., Zhang, K., Lu, T., Yin, X., Wang, Q., Xiong, L., Guo, H., Li, J., Lu, X., Liu, L., Ma, H. and Gao, Z. Structural and mechanistic basis for nitrile synthetase by an argininosuccinate synthetase-like enzyme. ACS Catalysis (2025) 16254–16267. [DOI]
[EC 4.2.1.186 created 2025]
 
 
EC 4.2.2.1     
Accepted name: hyaluronate lyase
Reaction: Cleaves hyaluronate chains at a β-D-GlcNAc-(1→4)-β-D-GlcA bond, ultimately breaking the polysaccharide down to 3-(4-deoxy-β-D-gluc-4-enuronosyl)-N-acetyl-D-glucosamine.
Other name(s): hyaluronidase (ambiguous); glucuronoglycosaminoglycan lyase (ambiguous); spreading factor; mucinase (ambiguous)
Systematic name: hyaluronate lyase
Comments: The enzyme catalyses the degradation of hyaluronan by a β-elimination reaction. Also acts on chondroitin. The product is more systematically known as 3-(4-deoxy-α-L-threo-hex-4-enopyranosyluronic acid)-2-acetamido-2-deoxy-D-glucose
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 37259-53-3
References:
1.  Linker, A., Hoffman, P., Meyer, K., Sampson, P. and Korn, E.D. The formation of unsaturated disacharides from mucopoly-saccharides and their cleavage to α-keto acid by bacterial enzymes. J. Biol. Chem. 235 (1960) 3061. [PMID: 13762462]
2.  Meyer, K. and Rapport, M.M. Hyaluronidases. Adv. Enzymol. Relat. Subj. Biochem. 13 (1952) 199–236. [PMID: 14943668]
3.  Moran, F., Nasuno, S. and Starr, M.P. Extracellular and intracellular polygalacturonic acid trans-eliminases of Erwinia carotovora. Arch. Biochem. Biophys. 123 (1968) 298–306. [DOI] [PMID: 5642600]
[EC 4.2.2.1 created 1961 as EC 4.2.99.1, transferred 1972 to EC 4.2.2.1, modified 2001]
 
 
EC 4.2.2.2     
Accepted name: pectate lyase
Reaction: Eliminative cleavage of (1→4)-α-D-galacturonan to give oligosaccharides with 4-deoxy-α-D-galact-4-enuronosyl groups at their non-reducing ends
For diagram of reaction, click here
Other name(s): polygalacturonic transeliminase; pectic acid transeliminase; polygalacturonate lyase; endopectin methyltranseliminase; pectate transeliminase; endogalacturonate transeliminase; pectic acid lyase; pectic lyase; α-1,4-D-endopolygalacturonic acid lyase; PGA lyase; PPase-N; endo-α-1,4-polygalacturonic acid lyase; polygalacturonic acid lyase; pectin trans-eliminase; Polygalacturonic acid trans-eliminase
Systematic name: (1→4)-α-D-galacturonan lyase
Comments: Favours pectate, the anion, over pectin, the methyl ester (which is the preferred substrate of EC 4.2.2.10, pectin lyase).
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9015-75-2
References:
1.  Albersheim, P. and Killias, U. Studies relating to the purification and properties of pectin transeliminase. Arch. Biochem. Biophys. 97 (1962) 107–115. [DOI] [PMID: 13860094]
2.  Edstrom, R.D. and Phaff, H.J. Purification and certain properties of pectin trans-eliminase from Aspergillus fonsecaeus. J. Biol. Chem. 239 (1964) 2403–2408. [PMID: 14235514]
3.  Edstrom, R.D. and Phaff, H.J. Eliminative cleavage of pectin and of oligogalacturonide methyl esters by pectin trans-eliminase. J. Biol. Chem. 239 (1964) 2409–2415. [PMID: 14235515]
4.  Nagel, C.W. and Vaughn, R.H. The degradation of oligogalacturonides by the polygalacturonase of Bacillus polymyxa. Arch. Biochem. Biophys. 94 (1961) 328. [DOI] [PMID: 13727438]
5.  Nasuno, S. and Starr, M.P. Polygalacturonic acid trans-eliminase of Xanthomonas campestris. Biochem. J. 104 (1967) 178–185. [PMID: 6035509]
6.  Mayans, O., Scott, M., Connerton, I., Gravesen, T., Benen, J., Visser, J., Pickersgill, R. and Jenkins, J. Two crystal structures of pectin lyase A from Aspergillus reveal a pH driven conformational change and striking divergence in the substrate-binding clefts of pectin and pectate lyases. Structure 5 (1997) 677–689. [DOI] [PMID: 9195887]
[EC 4.2.2.2 created 1965 as EC 4.2.99.3, transferred 1972 to EC 4.2.2.2, modified 2002]
 
 
EC 4.2.2.3     
Accepted name: mannuronate-specific alginate lyase
Reaction: Eliminative cleavage of alginate to give oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and β-D-mannuronate at their reducing end.
Other name(s): alginate lyase I; alginate lyase; alginase I; alginase II; alginase; poly(β-D-1,4-mannuronide) lyase; poly(β-D-mannuronate) lyase; aly (gene name) (ambiguous); poly[(1→4)-β-D-mannuronide] lyase
Systematic name: alginate β-D-mannuronate—uronate lyase
Comments: The enzyme catalyses the degradation of alginate by a β-elimination reaction. It cleaves the (1→4) bond between β-D-mannuronate and either α-L-guluronate or β-D-mannuronate, generating oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and β-D-mannuronate at the reducing end. Depending on the composition of the substrate, the enzyme produces oligosaccharides ranging from two to four residues, with preference for shorter products. cf. EC 4.2.2.11, guluronate-specific alginate lyase.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9024-15-1
References:
1.  Davidson, I.W., Lawson, C.J. and Sutherland, I.W. An alginate lysate from Azotobacter vinelandii phage. J. Gen. Microbiol. 98 (1977) 223–229. [DOI] [PMID: 13144]
2.  Nakada, H.I. and Sweeny, P.C. Alginic acid degradation by eliminases from abalone hepatopancreas. J. Biol. Chem. 242 (1967) 845–851. [PMID: 6020438]
3.  Preiss, J. and Ashwell, G. Alginic acid metabolism in bacteria. I. Enzymatic formation of unsaturated oligosaccharides and 4-deoxy-L-erythro-5-hexoseulose uronic acid. J. Biol. Chem. 237 (1962) 309–316. [PMID: 14488584]
[EC 4.2.2.3 created 1965 as EC 4.2.99.4, transferred 1972 to EC 4.2.2.3, modified 1990, modified 2015]
 
 
EC 4.2.2.4      
Transferred entry: chondroitin ABC lyase. Now known to comprise two enzymes: EC 4.2.2.20, chondroitin-sulfate-ABC endolyase and EC 4.2.2.21, chondroitin-sulfate-ABC exolyase
[EC 4.2.2.4 created 1972 (EC 4.2.99.6 created 1965, part incorporated 1976), deleted 2006]
 
 
EC 4.2.2.5     
Accepted name: chondroitin AC lyase
Reaction: Eliminative degradation of polysaccharides containing 1,4-β-D-hexosaminyl and 1,3-β-D-glucuronosyl linkages to disaccharides containing 4-deoxy-β-D-gluc-4-enuronosyl groups
Glossary: chondroitin sulfate A = chondroitin 4-sulfate
chondroitin sulfate C = chondroitin 6-sulfate
For the nomenclature of glycoproteins, glycopeptides and peptidoglycans, click here
Other name(s): chondroitinase (ambiguous); chondroitin sulfate lyase; chondroitin AC eliminase; chondroitinase AC; ChnAC
Systematic name: chondroitin AC lyase
Comments: Acts on chondroitin 4-sulfate and chondroitin 6-sulfate, but less well on hyaluronate. In general, chondroitin sulfate (CS) and dermatan sulfate (DS) chains comprise a linkage region, a chain cap and a repeat region. The repeat region of CS is a repeating disaccharide of glucuronic acid (GlcA) and N-acetylgalactosamine (GalNAc) [-4)GlcA(β1-3)GalNAc(β1-]n, which may be O-sulfated on the C-4 and/or C-6 of GalNAc and C-2 of GlcA. GlcA residues of CS may be epimerized to iduronic acid (IdoA) forming the repeating disaccharide [-4)IdoA(α1-3)GalNAc(β1-]n of DS. Both the concentrations and locations of sulfate-ester substituents vary with glucosaminoglycan source [4].
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9047-57-8
References:
1.  Nakada, H.I. and Wolfe, J.B. Studies on the enzyme chondroitinase: product structure and ion effects. Arch. Biochem. Biophys. 94 (1961) 244–251. [DOI] [PMID: 13727579]
2.  Pojasek, K., Shriver, Z., Kiley, P., Venkataraman, G. and Sasisekharan, R. Recombinant expression, purification, and kinetic characterization of chondroitinase AC and chondroitinase B from Flavobacterium heparinum. Biochem. Biophys. Res. Commun. 286 (2001) 343–351. [DOI] [PMID: 11500043]
3.  Fethiere, J., Shilton, B.H., Li, Y., Allaire, M., Laliberte, M., Eggimann, B. and Cygler, M. Crystallization and preliminary analysis of chondroitinase AC from Flavobacterium heparinum. Acta Crystallogr. D Biol. Crystallogr. 54 (1998) 279–280. [PMID: 9761894]
4.  Huckerby, T.N., Nieduszynski, I.A., Giannopoulos, M., Weeks, S.D., Sadler, I.H. and Lauder, R.M. Characterization of oligosaccharides from the chondroitin/dermatan sulfates. 1H-NMR and 13C-NMR studies of reduced trisaccharides and hexasaccharides. FEBS J. 272 (2005) 6276–6286. [DOI] [PMID: 16336265]
[EC 4.2.2.5 created 1972 (EC 4.2.99.6 created 1965, part incorporated 1976)]
 
 
EC 4.2.2.6     
Accepted name: oligogalacturonide lyase
Reaction: 4-(4-deoxy-α-D-galact-4-enuronosyl)-D-galacturonate = 2 5-dehydro-4-deoxy-D-glucuronate
Other name(s): oligogalacturonate lyase; unsaturated oligogalacturonate transeliminase; OGTE
Systematic name: oligogalacturonide lyase
Comments: Also catalyses eliminative removal of unsaturated terminal residues from oligosaccharides of D-galacturonate.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, CAS registry number: 9031-33-8
References:
1.  Moran, F., Nasuno, S. and Starr, M.P. Oligogalacturonide trans-eliminase of Erwinia carotovora. Arch. Biochem. Biophys. 125 (1968) 734–741. [DOI] [PMID: 5671040]
[EC 4.2.2.6 created 1972, modified 2010]
 
 
EC 4.2.2.7     
Accepted name: heparin lyase
Reaction: Eliminative cleavage of polysaccharides containing (1→4)-linked D-glucuronate or L-iduronate residues and (1→4)-α-linked 2-sulfoamino-2-deoxy-6-sulfo-D-glucose residues to give oligosaccharides with terminal 4-deoxy-α-D-gluc-4-enuronosyl groups at their non-reducing ends
Other name(s): heparin eliminase; heparinase
Systematic name: heparin lyase
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9025-39-2
References:
1.  Hovingh, P. and Linker, A. The enzymatic degradation of heparin and heparitin sulfate. 3. Purification of a heparitinase and a heparinase from flavobacteria. J. Biol. Chem. 245 (1970) 6170–6175. [PMID: 5484472]
[EC 4.2.2.7 created 1972]
 
 
EC 4.2.2.8     
Accepted name: heparin-sulfate lyase
Reaction: Elimination of sulfate; appears to act on linkages between N-acetyl-D-glucosamine and uronate. Product is an unsaturated sugar.
Other name(s): heparin-sulfate eliminase; heparitin-sulfate lyase; heparitinase I; heparitinase II
Systematic name: heparin-sulfate lyase
Comments: Does not act on N,O-desulfated glucosamine or N-acetyl-O-sulfated glucosamine linkages.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 37290-86-1
References:
1.  Hovingh, P. and Linker, A. The enzymatic degradation of heparin and heparitin sulfate. 3. Purification of a heparitinase and a heparinase from flavobacteria. J. Biol. Chem. 245 (1970) 6170–6175. [PMID: 5484472]
[EC 4.2.2.8 created 1972]
 
 
EC 4.2.2.9     
Accepted name: pectate disaccharide-lyase
Reaction: (1,4-α-D-galacturonosyl)n = (1,4-α-D-galacturonosyl)n-2 + 4-(4-deoxy-α-D-galact-4-enuronosyl)-D-galacturonate
For diagram of reaction, click here
Other name(s): pectate exo-lyase; exopectic acid transeliminase; exopectate lyase; exopolygalacturonic acid-trans-eliminase; PATE; exo-PATE; exo-PGL; exopolygalacturonate lyase (ambiguous); pelW (gene name); pelX (gene name)
Systematic name: (1→4)-α-D-galacturonan reducing-end-disaccharide-lyase
Comments: The enzyme catalyses the eliminative cleavage of an unsaturated disaccharide from the reducing end of homogalacturonan (the backbone of smooth regions of pectate, also known as de-esterified pectin).
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, CAS registry number: 37290-87-2
References:
1.  Macmillan, J.D. and Vaughn, R.H. Purification and properties of a polygalacturonic acid-trans-eliminase produced by Clostridium multifermentans. Biochemistry 3 (1964) 564–572. [PMID: 14188174]
2.  Shevchik, V.E., Kester, H.C., Benen, J.A., Visser, J., Robert-Baudouy, J. and Hugouvieux-Cotte-Pattat, N. Characterization of the exopolygalacturonate lyase PelX of Erwinia chrysanthemi 3937. J. Bacteriol. 181 (1999) 1652–1663. [PMID: 10049400]
3.  Shevchik, V.E., Condemine, G., Robert-Baudouy, J. and Hugouvieux-Cotte-Pattat, N. The exopolygalacturonate lyase PelW and the oligogalacturonate lyase Ogl, two cytoplasmic enzymes of pectin catabolism in Erwinia chrysanthemi 3937. J. Bacteriol. 181 (1999) 3912–3919. [PMID: 10383957]
[EC 4.2.2.9 created 1972, modified 2002]
 
 
EC 4.2.2.10     
Accepted name: pectin lyase
Reaction: Eliminative cleavage of (1→4)-α-D-galacturonan methyl ester to give oligosaccharides with 4-deoxy-6-O-methyl-α-D-galact-4-enuronosyl groups at their non-reducing ends
For diagram of reaction, click here
Other name(s): pectin trans-eliminase; endo-pectin lyase; polymethylgalacturonic transeliminase; pectin methyltranseliminase; pectolyase; PL; PNL; PMGL
Systematic name: (1→4)-6-O-methyl-α-D-galacturonan lyase
Comments: Favours pectin, the methyl ester, over pectate, the anion (which is the preferred substrate of EC 4.2.2.2, pectate lyase). Demethylation progressively slows its action; it can nevertheless cleave on either side of a demethylated residue if the residue at the other end of the scissile bond is methylated.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9033-35-6
References:
1.  Albersheim, P., Neukom, H. and Deuel, H. Über die Bildung von ungesättigten Abbauprodukten durch ein pekinabbauendes Enzym. Helv. Chim. Acta 43 (1960) 1422–1426.
2.  Mayans, O., Scott, M., Connerton, I., Gravesen, T., Benen, J., Visser, J., Pickersgill, R. and Jenkins, J. Two crystal structures of pectin lyase A from Aspergillus reveal a pH driven conformational change and striking divergence in the substrate-binding clefts of pectin and pectate lyases. Structure 5 (1997) 677–689. [DOI] [PMID: 9195887]
3.  Kester, H.C.M and Visser, J. Purification and characterization of pectin lyase B, a novel pectinolytic enzyme from Aspergillus niger. FEMS Microbiol. Lett. 120 (1994) 63–68.
4.  Mutenda, K.E., Körner, R., Christensen, T.M.I.E., Mikkelsen, J. and Roepstorff, P. Application of mass spectrometry to determine the activity and specificity of pectin lyase A. Carbohydr. Res. 337 (2002) 1213–1223. [DOI] [PMID: 12110197]
[EC 4.2.2.10 created 1972, modified 2002]
 
 
EC 4.2.2.11     
Accepted name: guluronate-specific alginate lyase
Reaction: Eliminative cleavage of alginate to give oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and α-L-guluronate at their reducing end.
Other name(s): alginase II; guluronate lyase; L-guluronan lyase; L-guluronate lyase; poly-α-L-guluronate lyase; polyguluronate-specific alginate lyase; poly(α-L-1,4-guluronide) exo-lyase; poly(α-L-guluronate) lyase; poly[(1→4)-α-L-guluronide] exo-lyase
Systematic name: alginate α-L-guluronate—uronate lyase
Comments: The enzyme catalyses the degradation of alginate by a β-elimination reaction. It cleaves the (1→4) bond between α-L-guluronate and either α-L-guluronate or β-D-mannuronate, generating oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enuronosyl groups at their non-reducing ends and α-L-guluronate at the reducing end. Depending on the composition of the substrate, the enzyme produces oligosaccharides ranging from two to six residues, with preference for shorter products. cf. EC 4.2.2.3, mannuronate-specific alginate lyase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 64177-88-4
References:
1.  Boyd, J. and Turvey, J.R. Isolation of poly-α-L-guluronate lyase from Klebsiella aerogenes. Carbohydr. Res. 57 (1977) 163–171. [PMID: 332364]
2.  Davidson, I.W., Sutherland, I.W. and Lawson, C.J. Purification and properties of an alginate lyase from a marine bacterium. Biochem. J. 159 (1976) 707–713. [PMID: 1008828]
[EC 4.2.2.11 created 1990, modified 2015]
 
 
EC 4.2.2.12     
Accepted name: xanthan lyase
Reaction: Eliminative cleavage of the terminal β-D-mannosyl-(1→4)-β-D-glucuronosyl linkage of the side-chain of the polysaccharide xanthan, leaving a 4-deoxy-α-L-threo-hex-4-enuronosyl group at the terminus of the side-chain
Systematic name: xanthan lyase
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 113573-69-6
References:
1.  Sutherland, I.W. Xanthan lyases-novel enzymes found in various bacterial species. J. Gen. Microbiol. 133 (1987) 3129–3134. [DOI] [PMID: 3446747]
[EC 4.2.2.12 created 1990]
 
 
EC 4.2.2.13     
Accepted name: exo-(1→4)-α-D-glucan lyase
Reaction: linear α-glucan = (n-1) 1,5-anhydro-D-fructose + D-glucose
For diagram of the anhydrofructose pathway, click here
Other name(s): α-(1→4)-glucan 1,5-anhydro-D-fructose eliminase; α-1,4-glucan exo-lyase; α-1,4-glucan lyase; GLase
Systematic name: (1→4)-α-D-glucan exo-4-lyase (1,5-anhydro-D-fructose-forming)
Comments: The enzyme catalyses the sequential degradation of (1→4)-α-D-glucans from the non-reducing end with the release of 1,5-anhydro-D-fructose. Thus, for an α-glucan containing n (1→4)-linked glucose units, the final products are 1 glucose plus (n-1) 1,5-anhydro-D-fructose. Maltose, maltosaccharides and amylose are all completely degraded. It does not degrade (1→6)-α-glucosidic bonds and thus the degradation of a branched glucan, such as amylopectin or glycogen, will result in the formation of 1,5-anhydro-D-fructose plus a limit dextrin. Other enzymes involved in the anhydrofructose pathway are EC 4.2.1.110 (aldos-2-ulose dehydratase), EC 4.2.1.111 (1,5-anhydro-D-fructose dehydratase) and EC 5.3.2.7 (ascopyrone tautomerase).
Links to other databases: BRENDA, EAWAG-BBD, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 148710-18-3
References:
1.  Yu, S., Kenne, L., Pedersén, M. α-1,4-Glucan lyase, a new class of starch/glycogen degrading enzyme. I. Efficient purification and characterization from red seaweeds. Biochim. Biophys. Acta 1156 (1993) 313–320. [DOI] [PMID: 8461323]
2.  Yu, S., Pedersén, M. α-1,4-Glucan lyase, a new class of starch/glycogen degrading enzyme. II. Subcellular localization and partial amino-acid sequence. Planta 191 (1993) 137–142. [PMID: 7763826]
3.  Yu, S., Ahmad, T., Kenne, L. and Pedersén, M. α-1,4-Glucan lyase, a new class of starch/glycogen degrading enzyme. III. Substrate specificity, mode of action, and cleavage mechanism. Biochim. Biophys. Acta 1244 (1995) 1–9. [DOI] [PMID: 7766642]
4.  Yu, S., Christensen, T.M., Kragh, K.M., Bojsen, K. and Marcussen, J. Efficient purification, characterization and partial amino acid sequencing of two α-1,4-glucan lyases from fungi. Biochim. Biophys. Acta 1339 (1997) 311–320. [DOI] [PMID: 9187252]
5.  Yu, S., Bojsen, K., Svensson, B. and Marcussen, J. α-1,4-glucan lyases producing 1,5-anhydro-D-fructose from starch and glycogen have sequence similarity to α-glucosidases. Biochim. Biophys. Acta 1433 (1999) 1–15. [DOI] [PMID: 10446355]
6.  Lee, S.S., Yu, S. and Withers, S.G. α-1,4-Glucan lyase performs a trans-elimination via a nucleophilic displacement followed by a syn-elimination. J. Am. Chem. Soc. 124 (2002) 4948–4949. [DOI] [PMID: 11982345]
7.  Lee, S.S., Yu, S. and Withers, S.G. Detailed dissection of a new mechanism for glycoside cleavage: α-1,4-glucan lyase. Biochemistry 42 (2003) 13081–13090. [DOI] [PMID: 14596624]
[EC 4.2.2.13 created 1999]
 
 
EC 4.2.2.14     
Accepted name: glucuronan lyase
Reaction: Eliminative cleavage of (1→4)-β-D-glucuronans to give oligosaccharides with 4-deoxy-β-D-gluc-4-enuronosyl groups at their non-reducing ends. Complete degradation of glucuronans results in the formation of tetrasaccharides.
For diagram of reaction, click here
Other name(s): (1,4)-β-D-glucuronan lyase
Systematic name: (1→4)-β-D-glucuronan lyase
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 193766-71-1
References:
1.  Michaud, P., Pheulpin, P., Petit, E., Seguin, J.P., Barbotin, J.N., Heyraud, A., Courtois, B. and Courtois, J. Identification of glucuronan lyase from a mutant strain of Rhizobium meliloti. Int. J. Biol. Macromol. 21 (1997) 3–9. [DOI] [PMID: 9283009]
[EC 4.2.2.14 created 2000]
 
 
EC 4.2.2.15     
Accepted name: anhydrosialidase
Reaction: Elimination of α-sialyl groups in N-acetylneuraminic acid glycosides, releasing 2,7-anhydro-α-N-acetylneuraminate
For diagram of reaction, click here
Other name(s): anhydroneuraminidase; sialglycoconjugate N-acylneuraminylhydrolase (2,7-cyclizing); sialidase L
Systematic name: glycoconjugate sialyl-lyase (2,7-cyclizing)
Comments: Also acts on N-glycolylneuraminate glycosides. cf. EC 3.2.1.18 (exo-α-sialidase) and EC 3.2.1.129 (endo-α-sialidase).
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 157857-11-9
References:
1.  Li, Y.-T., Nakagawa, H., Ross, S.A., Hansson, G.C. and Li, S.C. A novel sialidase which releases 2,7-anhydro-α-N-acetylneuraminic acid from sialoglycoconjugates. J. Biol. Chem. 265 (1990) 21629–21633. [PMID: 2254319]
[EC 4.2.2.15 created 1992 as EC 3.2.1.138, transferred 2003 to EC 4.2.2.15]
 
 
EC 4.2.2.16     
Accepted name: levan fructotransferase (DFA-IV-forming)
Reaction: Produces di-β-D-fructofuranose 2,6′:2′,6-dianhydride (DFA IV) by successively eliminating the diminishing (2→6)-β-D-fructan (levan) chain from the terminal D-fructosyl-D-fructosyl disaccharide
For diagram of reaction, click here
Other name(s): 2,6-β-D-fructan D-fructosyl-D-fructosyltransferase (forming di-β-D-fructofuranose 2,6′:2′,6-dianhydride); levan fructotransferase; 2,6-β-D-fructan lyase (di-β-D-fructofuranose-2,6′:2′,6-dianhydride-forming)
Systematic name: (2→6)-β-D-fructan lyase (di-β-D-fructofuranose-2,6′:2′,6-dianhydride-forming)
Comments: This enzyme, like EC 4.2.2.17 [inulin fructotransferase (DFA-I-forming)] and EC 4.2.2.18 [inulin fructotransferase (DFA-III-forming)], sequentially eliminates disaccharides from the non-reducing terminus of the fructan chain, with the disaccharide leaving as a difructose dianhydride. These enzymes have long been known as fructotransferases, so this is retained in the accepted name. Since the transfer is intramolecular, the reaction is an elimination and, hence, the enzyme is a lyase, belonging in EC 4.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 88593-15-1
References:
1.  Song, K.B., Bae, K.S., Lee, Y.B., Lee, K.Y. and Rhee, S.K. Characteristics of levan fructotransferase from Arthrobacter ureafaciens K2032 and difructose anhydride IV formation from levan. Enzyme Microb. Technol. 27 (2000) 212–218. [DOI] [PMID: 10899545]
2.  Jang, K.H., Ryu, E.J., Park, B.S., Song, K.B., Kang, S.A., Kim, C.H., Uhm, T.B., Park, Y.I. and Rhee, S.K. Levan fructotransferase from Arthrobacter oxydans, J 17-21 catalyzes the formation of the di-D-fructose dianhydride IV from levan. J. Agric. Food Chem. 51 (2003) 2632–2636. [DOI] [PMID: 12696949]
3.  Saito, K. and Tomita, F. Difructose anhydrides: Their mass-production and physiological functions. Biosci. Biotechnol. Biochem. 64 (2000) 1321–1327. [DOI] [PMID: 10945246]
[EC 4.2.2.16 created 2004, modified 2025]
 
 
EC 4.2.2.17     
Accepted name: inulin fructotransferase (DFA-I-forming)
Reaction: Produces α-D-fructofuranose β-D-fructofuranose 1,2′:2,1′-dianhydride (DFA I) by successively eliminating the diminishing (2→1)-β-D-fructan (inulin) chain from the terminal D-fructosyl-D-fructosyl disaccharide.
For diagram of reaction, click here
Other name(s): inulin fructotransferase (DFA-I-producing); inulin fructotransferase (depolymerizing, difructofuranose-1,2′:2′,1-dianhydride-forming); inulin D-fructosyl-D-fructosyltransferase (1,2′:1′,2-dianhydride-forming); inulin D-fructosyl-D-fructosyltransferase (forming α-D-fructofuranose β-D-fructofuranose 1,2′:1′,2-dianhydride); 2,1-β-D-fructan lyase (α-D-fructofuranose-β-D-fructofuranose-1,2′:2,1′-dianhydride-forming)
Systematic name: (2→1)-β-D-fructan lyase (α-D-fructofuranose-β-D-fructofuranose-1,2′:2,1′-dianhydride-forming)
Comments: This enzyme, like EC 4.2.2.16 [levan fructotransferase (DFA-IV-forming)] and EC 4.2.2.18 [inulin fructotransferase (DFA-III-forming)], sequentially eliminates disaccharides from the non-reducing terminus of the fructan chain, with the disaccharide leaving as a difructose dianhydride. These enzymes have long been known as fructotransferases, so this is retained in the accepted name. Since the transfer is intramolecular, the reaction is an elimination and, hence, the enzyme is a lyase, belonging in EC 4.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 125008-19-7
References:
1.  Seki, K., Haraguchi, K., Kishimoto, M., Kobayashi, S. and Kainuma, K. Purification and properties of a novel inulin fructotransferase (DFA I-producing) from Arthrobacter globiformis S14-3. Agric. Biol. Chem. 53 (1989) 2089–2094. [DOI]
[EC 4.2.2.17 created 1992 as EC 2.4.1.200, transferred 2004 to EC 4.2.2.17, modified 2025]
 
 
EC 4.2.2.18     
Accepted name: inulin fructotransferase (DFA-III-forming)
Reaction: Produces α-D-fructofuranose β-D-fructofuranose 1,2′:2,3′-dianhydride (DFA III) by successively eliminating the diminishing (2→1)-β-D-fructan (inulin) chain from the terminal D-fructosyl-D-fructosyl disaccharide.
For diagram of reaction, click here
Other name(s): inulin fructotransferase (DFA-III-producing); inulin fructotransferase (depolymerizing); inulase II; inulinase II; inulin fructotransferase (depolymerizing, difructofuranose-1,2′:2,3′-dianhydride-forming); inulin D-fructosyl-D-fructosyltransferase (1,2′:2,3′-dianhydride-forming); inulin D-fructosyl-D-fructosyltransferase (forming α-D-fructofuranose β-D-fructofuranose 1,2′:2,3′-dianhydride); 2,1-β-D-fructan lyase (α-D-fructofuranose-β-D-fructofuranose-1,2′:2,3′-dianhydride-forming)
Systematic name: (2→1)-β-D-fructan lyase (α-D-fructofuranose-β-D-fructofuranose-1,2′:2,3′-dianhydride-forming)
Comments: This enzyme, like EC 4.2.2.16 [levan fructotransferase (DFA-IV-forming)] and EC 4.2.2.17 [inulin fructotransferase (DFA-I-forming)], sequentially eliminates disaccharides from the non-reducing terminus of the fructan chain, with the disaccharide leaving as a difructose dianhydride. These enzymes have long been known as fructotransferases, so this is retained in the accepted name. Since the transfer is intramolecular, the reaction is an elimination and, hence, the enzyme is a lyase, belonging in EC 4.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 50936-42-0
References:
1.  Uchiyama, T. Action of Arthrobacter ureafaciens inulinase II on several oligofructans and bacterial levans. Biochim. Biophys. Acta 397 (1975) 153–163. [DOI] [PMID: 1148257]
2.  Uchiyama, T., Niwa, S. and Tanaka, K. Purification and properties of Arthrobacter ureafaciens inulase II. Biochim. Biophys. Acta 315 (1973) 412–420. [DOI]
[EC 4.2.2.18 created 1976 as EC 2.4.1.93, transferred 2004 to EC 4.2.2.18, modified 2025]
 
 
EC 4.2.2.19     
Accepted name: chondroitin B lyase
Reaction: Eliminative cleavage of dermatan sulfate containing (1→4)-β-D-hexosaminyl and (1→3)-β-D-glucurosonyl or (1→3)-α-L-iduronosyl linkages to disaccharides containing 4-deoxy-β-D-gluc-4-enuronosyl groups to yield a 4,5-unsaturated dermatan-sulfate disaccharide (ΔUA-GalNAc-4S).
Glossary: chondroitin sulfate B = dermatan sulfate
For the nomenclature of glycoproteins, glycopeptides and peptidoglycans, click here
Other name(s): chondroitinase B; ChonB; ChnB
Systematic name: chondroitin B lyase
Comments: This is the only lyase that is known to be specific for dermatan sulfate as substrate. The minimum substrate length required for catalysis is a tetrasaccharide [2]. In general, chondroitin sulfate (CS) and dermatan sulfate (DS) chains comprise a linkage region, a chain cap and a repeat region. The repeat region of CS is a repeating disaccharide of glucuronic acid (GlcA) and N-acetylgalactosamine (GalNAc) [-4)GlcA(β1-3)GalNAc(β1-]n, which may be O-sulfated on the C-4 and/or C-6 of GalNAc and C-2 of GlcA. GlcA residues of CS may be epimerized to iduronic acid (IdoA) forming the repeating disaccharide [-4)IdoA(α1-3)GalNAc(β1-]n of DS. Both the concentrations and locations of sulfate-ester substituents vary with glucosaminoglycan source [5].
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 52227-83-5
References:
1.  Gu, K., Linhardt, R.J., Laliberte, M., Gu, K. and Zimmermann, J. Purification, characterization and specificity of chondroitin lyases and glycuronidase from Flavobacterium heparinum. Biochem. J. 312 (1995) 569–577. [PMID: 8526872]
2.  Pojasek, K., Raman, R., Kiley, P., Venkataraman, G. and Sasisekharan, R. Biochemical characterization of the chondroitinase B active site. J. Biol. Chem. 277 (2000) 31179–31186. [DOI] [PMID: 12063249]
3.  Pojasek, K., Shriver, Z., Kiley, P., Venkataraman, G. and Sasisekharan, R. Recombinant expression, purification, and kinetic characterization of chondroitinase AC and chondroitinase B from Flavobacterium heparinum. Biochem. Biophys. Res. Commun. 286 (2001) 343–351. [DOI] [PMID: 11500043]
4.  Suzuki, K., Terasaki, Y. and Uyeda, M. Inhibition of hyaluronidases and chondroitinases by fatty acids. J. Enzyme 17 (2002) 183–186. [DOI] [PMID: 12443044]
5.  Ototani, N. and Yosizawa, Z. Purification of chondroitinase B and chondroitinase C using glycosaminoglycan-bound AH-Sepharose 4B. Carbohydr. Res. 70 (1979) 295–306. [DOI] [PMID: 427837]
6.  Tkalec, A.L., Fink, D., Blain, F., Zhang-Sun, G., Laliberte, M., Bennett, D.C., Gu, K., Zimmermann, J.J. and Su, H. Isolation and expression in Escherichia coli of cslA and cslB, genes coding for the chondroitin sulfate-degrading enzymes chondroitinase AC and chondroitinase B, respectively, from Flavobacterium heparinum. Appl. Environ. Microbiol. 66 (2000) 29–35. [DOI] [PMID: 10618199]
7.  Michel, G., Pojasek, K., Li, Y., Sulea, T., Linhardt, R.J., Raman, R., Prabhakar, V., Sasisekharan, R. and Cygler, M. The structure of chondroitin B lyase complexed with glycosaminoglycan oligosaccharides unravels a calcium-dependent catalytic machinery. J. Biol. Chem. 279 (2004) 32882–32896. [DOI] [PMID: 15155751]
8.  Li, Y., Matte, A., Su, H. and Cygler, M. Crystallization and preliminary X-ray analysis of chondroitinase B from Flavobacterium heparinum. Acta Crystallogr. D Biol. Crystallogr. 55 (1999) 1055–1057. [PMID: 10216304]
9.  Huang, W., Matte, A., Li, Y., Kim, Y.S., Linhardt, R.J., Su, H. and Cygler, M. Crystal structure of chondroitinase B from Flavobacterium heparinum and its complex with a disaccharide product at 1.7 Å resolution. J. Mol. Biol. 294 (1999) 1257–1269. [DOI] [PMID: 10600383]
10.  Huckerby, T.N., Nieduszynski, I.A., Giannopoulos, M., Weeks, S.D., Sadler, I.H. and Lauder, R.M. Characterization of oligosaccharides from the chondroitin/dermatan sulfates. 1H-NMR and 13C-NMR studies of reduced trisaccharides and hexasaccharides. FEBS J. 272 (2005) 6276–6286. [DOI] [PMID: 16336265]
[EC 4.2.2.19 created 2005]
 
 
EC 4.2.2.20     
Accepted name: chondroitin-sulfate-ABC endolyase
Reaction: Endolytic cleavage of (1→4)-β-galactosaminic bonds between N-acetylgalactosamine and either D-glucuronic acid or L-iduronic acid to produce a mixture of Δ4-unsaturated oligosaccharides of different sizes that are ultimately degraded to Δ4-unsaturated tetra- and disaccharides
For diagram of reaction click here
Glossary: chondroitin sulfate A = chondroitin 4-sulfate
chondroitin sulfate B = dermatan sulfate
chondroitin sulfate C = chondroitin 6-sulfate
For the nomenclature of glycoproteins, glycopeptides and peptidoglycans, click here
Other name(s): chondroitinase (ambiguous); chondroitin ABC eliminase (ambiguous); chondroitinase ABC (ambiguous); chondroitin ABC lyase (ambiguous); chondroitin sulfate ABC lyase (ambiguous); ChS ABC lyase (ambiguous); chondroitin sulfate ABC endoeliminase; chondroitin sulfate ABC endolyase; ChS ABC lyase I
Systematic name: chondroitin-sulfate-ABC endolyase
Comments: This enzyme degrades a variety of glycosaminoglycans of the chondroitin-sulfate- and dermatan-sulfate type. Chondroitin sulfate, chondroitin-sulfate proteoglycan and dermatan sulfate are the best substrates but the enzyme can also act on hyaluronan at a much lower rate. Keratan sulfate, heparan sulfate and heparin are not substrates. In general, chondroitin sulfate (CS) and dermatan sulfate (DS) chains comprise a linkage region, a chain cap and a repeat region. The repeat region of CS is a repeating disaccharide of glucuronic acid (GlcA) and N-acetylgalactosamine (GalNAc) [-4)GlcA(β1-3)GalNAc(β1-]n, which may be O-sulfated on the C-4 and/or C-6 of GalNAc and C-2 of GlcA. GlcA residues of CS may be epimerized to iduronic acid (IdoA) forming the repeating disaccharide [-4)IdoA(α1-3)GalNAc(β1-]n of DS. Both the concentrations and locations of sulfate-ester substituents vary with glucosaminoglycan source [5]. The related enzyme EC 4.2.2.21, chondroitin-sulfate-ABC exolyase, has the same substrate specificity but removes disaccharide residues from the non-reducing ends of both polymeric chondroitin sulfates and their oligosaccharide fragments produced by EC 4.2.2.20 [4].
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9024-13-9
References:
1.  Yamagata, T., Saito, H., Habuchi, O. and Suzuki, S. Purification and properties of bacterial chondroitinases and chondrosulfatases. J. Biol. Chem. 243 (1968) 1523–1535. [PMID: 5647268]
2.  Saito, H., Yamagata, T. and Suzuki, S. Enzymatic methods for the determination of small quantities of isomeric chondroitin sulfates. J. Biol. Chem. 243 (1968) 1536–1542. [PMID: 4231029]
3.  Suzuki, S., Saito, H., Yamagata, T., Anno, K., Seno, N., Kawai, Y. and Furuhashi, T. Formation of three types of disulfated disaccharides from chondroitin sulfates by chondroitinase digestion. J. Biol. Chem. 243 (1968) 1543–1550. [PMID: 5647269]
4.  Hamai, A., Hashimoto, N., Mochizuki, H., Kato, F., Makiguchi, Y., Horie, K. and Suzuki, S. Two distinct chondroitin sulfate ABC lyases. An endoeliminase yielding tetrasaccharides and an exoeliminase preferentially acting on oligosaccharides. J. Biol. Chem. 272 (1997) 9123–9130. [DOI] [PMID: 9083041]
5.  Huckerby, T.N., Nieduszynski, I.A., Giannopoulos, M., Weeks, S.D., Sadler, I.H. and Lauder, R.M. Characterization of oligosaccharides from the chondroitin/dermatan sulfates. 1H-NMR and 13C-NMR studies of reduced trisaccharides and hexasaccharides. FEBS J. 272 (2005) 6276–6286. [DOI] [PMID: 16336265]
[EC 4.2.2.20 created 2006 (EC 4.2.2.4 created 1972, part-incorporated 2006 (EC 4.2.99.6 created 1965, part incorporated 1976))]
 
 
EC 4.2.2.21     
Accepted name: chondroitin-sulfate-ABC exolyase
Reaction: Exolytic removal of Δ4-unsaturated disaccharide residues from the non-reducing ends of both polymeric chondroitin/dermatan sulfates and their oligosaccharide fragments.
For diagram of reaction click here
Glossary: chondroitin sulfate A = chondroitin 4-sulfate
chondroitin sulfate B = dermatan sulfate
chondroitin sulfate C = chondroitin 6-sulfate
For the nomenclature of glycoproteins, glycopeptides and peptidoglycans, click here
Other name(s): chondroitinase (ambiguous); chondroitin ABC eliminase (ambiguous); chondroitinase ABC (ambiguous); chondroitin ABC lyase (ambiguous); chondroitin sulfate ABC lyase (ambiguous); ChS ABC lyase (ambiguous); chondroitin sulfate ABC exoeliminase; chondroitin sulfate ABC exolyase; ChS ABC lyase II
Systematic name: chondroitin-sulfate-ABC exolyase
Comments: This enzyme degrades a variety of glycosaminoglycans of the chondroitin-sulfate- and dermatan-sulfate type. Chondroitin sulfate, chondroitin-sulfate proteoglycan and dermatan sulfate are the best substrates but the enzyme can also act on hyaluronan at a much lower rate. Keratan sulfate, heparan sulfate and heparin are not substrates. The related enzyme EC 4.2.2.20, chondroitin-sulfate-ABC endolyase, has the same substrate specificity but produces a mixture of oligosaccharides of different sizes that are ultimately degraded to tetra- and disaccharides [4]. Both enzymes act by the removal of a relatively acidic C-5 proton of the uronic acid followed by the elimination of a 4-linked hexosamine, resulting in the formation of an unsaturated C4—C5 bond on the hexuronic acid moiety of the products [4,6].
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 1000607-06-6
References:
1.  Yamagata, T., Saito, H., Habuchi, O. and Suzuki, S. Purification and properties of bacterial chondroitinases and chondrosulfatases. J. Biol. Chem. 243 (1968) 1523–1535. [PMID: 5647268]
2.  Saito, H., Yamagata, T. and Suzuki, S. Enzymatic methods for the determination of small quantities of isomeric chondroitin sulfates. J. Biol. Chem. 243 (1968) 1536–1542. [PMID: 4231029]
3.  Suzuki, S., Saito, H., Yamagata, T., Anno, K., Seno, N., Kawai, Y. and Furuhashi, T. Formation of three types of disulfated disaccharides from chondroitin sulfates by chondroitinase digestion. J. Biol. Chem. 243 (1968) 1543–1550. [PMID: 5647269]
4.  Hamai, A., Hashimoto, N., Mochizuki, H., Kato, F., Makiguchi, Y., Horie, K. and Suzuki, S. Two distinct chondroitin sulfate ABC lyases. An endoeliminase yielding tetrasaccharides and an exoeliminase preferentially acting on oligosaccharides. J. Biol. Chem. 272 (1997) 9123–9130. [DOI] [PMID: 9083041]
5.  Huckerby, T.N., Nieduszynski, I.A., Giannopoulos, M., Weeks, S.D., Sadler, I.H. and Lauder, R.M. Characterization of oligosaccharides from the chondroitin/dermatan sulfates. 1H-NMR and 13C-NMR studies of reduced trisaccharides and hexasaccharides. FEBS J. 272 (2005) 6276–6286. [DOI] [PMID: 16336265]
6.  Zhang, Z., Park, Y., Kemp, M.M., Zhao, W., Im, A.R., Shaya, D., Cygler, M., Kim, Y.S. and Linhardt, R.J. Liquid chromatography-mass spectrometry to study chondroitin lyase action pattern. Anal. Biochem. 385 (2009) 57–64. [DOI] [PMID: 18992215]
[EC 4.2.2.21 created 2006 (EC 4.2.2.4 created 1972, part-incorporated 2006 (EC 4.2.99.6 created 1965, part incorporated 1976)), modified 2010]
 
 
EC 4.2.2.22     
Accepted name: pectate trisaccharide-lyase
Reaction: eliminative cleavage of unsaturated trigalacturonate as the major product from the reducing end of polygalacturonic acid/pectate
Other name(s): exopectate-lyase; pectate lyase A; PelA
Systematic name: (1→4)-α-D-galacturonan reducing-end-trisaccharide-lyase
Comments: Differs in specificity from EC 4.2.2.9, pectate disaccharide-lyase, as the predominant action is removal of a trisaccharide rather than a disaccharide from the reducing end. Disaccharides and tetrasaccharides may also be removed [2].
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB
References:
1.  Kluskens, L.D., van Alebeek, G.J., Voragen, A.G., de Vos, W.M. and van der Oost, J. Molecular and biochemical characterization of the thermoactive family 1 pectate lyase from the hyperthermophilic bacterium Thermotoga maritima. Biochem. J. 370 (2003) 651–659. [DOI] [PMID: 12443532]
2.  Tamaru, Y. and Doi, R.H. Pectate lyase A, an enzymatic subunit of the Clostridium cellulovorans cellulosome. Proc. Natl. Acad. Sci. USA 98 (2001) 4125–4129. [DOI] [PMID: 11259664]
3.  Berensmeier, S., Singh, S.A., Meens, J. and Buchholz, K. Cloning of the pelA gene from Bacillus licheniformis 14A and biochemical characterization of recombinant, thermostable, high-alkaline pectate lyase. Appl. Microbiol. Biotechnol. 64 (2004) 560–567. [DOI] [PMID: 14673544]
[EC 4.2.2.22 created 2007]
 
 
EC 4.2.2.23     
Accepted name: rhamnogalacturonan endolyase
Reaction: Endotype eliminative cleavage of L-α-rhamnopyranosyl-(1→4)-α-D-galactopyranosyluronic acid bonds of rhamnogalacturonan I domains in ramified hairy regions of pectin leaving L-rhamnopyranose at the reducing end and 4-deoxy-4,5-unsaturated D-galactopyranosyluronic acid at the non-reducing end.
Other name(s): rhamnogalacturonase B; α-L-rhamnopyranosyl-(1→4)-α-D-galactopyranosyluronide lyase; Rgase B; rhamnogalacturonan α-L-rhamnopyranosyl-(1,4)-α-D-galactopyranosyluronide lyase; RG-lyase; YesW; RGL4; Rgl11A; Rgl11Y; RhiE
Systematic name: α-L-rhamnopyranosyl-(1→4)-α-D-galactopyranosyluronate endolyase
Comments: The enzyme is part of the degradation system for rhamnogalacturonan I in Bacillus subtilis strain 168 and Aspergillus aculeatus.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB
References:
1.  Mutter, M., Colquhoun, I.J., Schols, H.A., Beldman, G. and Voragen, A.G. Rhamnogalacturonase B from Aspergillus aculeatus is a rhamnogalacturonan α-L-rhamnopyranosyl-(1→4)-α-D-galactopyranosyluronide lyase. Plant Physiol. 110 (1996) 73–77. [PMID: 8587995]
2.  Azadi, P., O'Neill, M.A., Bergmann, C., Darvill, A.G. and Albersheim, P. The backbone of the pectic polysaccharide rhamnogalacturonan I is cleaved by an endohydrolase and an endolyase. Glycobiology 5 (1995) 783–789. [DOI] [PMID: 8720076]
3.  Mutter, M., Colquhoun, I.J., Beldman, G., Schols, H.A., Bakx, E.J. and Voragen, A.G. Characterization of recombinant rhamnogalacturonan α-L-rhamnopyranosyl-(1,4)-α-D-galactopyranosyluronide lyase from Aspergillus aculeatus. An enzyme that fragments rhamnogalacturonan I regions of pectin. Plant Physiol. 117 (1998) 141–152. [PMID: 9576783]
4.  Kadirvelraj, R., Harris, P., Poulsen, J.C., Kauppinen, S. and Larsen, S. A stepwise optimization of crystals of rhamnogalacturonan lyase from Aspergillus aculeatus. Acta Crystallogr. D Biol. Crystallogr. 58 (2002) 1346–1349. [PMID: 12136151]
5.  Laatu, M. and Condemine, G. Rhamnogalacturonate lyase RhiE is secreted by the out system in Erwinia chrysanthemi. J. Bacteriol. 185 (2003) 1642–1649. [DOI] [PMID: 12591882]
6.  Pages, S., Valette, O., Abdou, L., Belaich, A. and Belaich, J.P. A rhamnogalacturonan lyase in the Clostridium cellulolyticum cellulosome. J. Bacteriol. 185 (2003) 4727–4733. [DOI] [PMID: 12896991]
7.  Ochiai, A., Yamasaki, M., Itoh, T., Mikami, B., Hashimoto, W. and Murata, K. Crystallization and preliminary X-ray analysis of the rhamnogalacturonan lyase YesW from Bacillus subtilis strain 168, a member of polysaccharide lyase family 11. Acta Crystallogr. Sect. F Struct. Biol. Cryst. Commun. 62 (2006) 438–440. [DOI] [PMID: 16682770]
8.  Jensen, M.H., Otten, H., Christensen, U., Borchert, T.V., Christensen, L.L., Larsen, S. and Leggio, L.L. Structural and biochemical studies elucidate the mechanism of rhamnogalacturonan lyase from Aspergillus aculeatus. J. Mol. Biol. 404 (2010) 100–111. [DOI] [PMID: 20851126]
[EC 4.2.2.23 created 2011]
 
 
EC 4.2.2.24     
Accepted name: rhamnogalacturonan exolyase
Reaction: Exotype eliminative cleavage of α-L-rhamnopyranosyl-(1→4)-α-D-galactopyranosyluronic acid bonds of rhamnogalacturonan I oligosaccharides containing α-L-rhamnopyranose at the reducing end and 4-deoxy-4,5-unsaturated D-galactopyranosyluronic acid at the non-reducing end. The products are the disaccharide 2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-rhamnopyranose and the shortened rhamnogalacturonan oligosaccharide containing one 4-deoxy-4,5-unsaturated D-galactopyranosyluronic acid at the non-reducing end.
For diagram of ramnosylgalacturan degradation, click here
Glossary: 6-deoxy-2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-mannopyranose = 2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-rhamnopyranose
Other name(s): YesX
Systematic name: α-L-rhamnopyranosyl-(1→4)-α-D-galactopyranosyluronate exolyase
Comments: The enzyme is part of the degradation system for rhamnogalacturonan I in Bacillus subtilis strain 168.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB
References:
1.  Ochiai, A., Itoh, T., Mikami, B., Hashimoto, W. and Murata, K. Structural determinants responsible for substrate recognition and mode of action in family 11 polysaccharide lyases. J. Biol. Chem. 284 (2009) 10181–10189. [DOI] [PMID: 19193638]
2.  Ochiai, A., Itoh, T., Kawamata, A., Hashimoto, W. and Murata, K. Plant cell wall degradation by saprophytic Bacillus subtilis strains: gene clusters responsible for rhamnogalacturonan depolymerization. Appl. Environ. Microbiol. 73 (2007) 3803–3813. [DOI] [PMID: 17449691]
[EC 4.2.2.24 created 2011]
 
 
EC 4.2.2.25     
Accepted name: gellan lyase
Reaction: Eliminative cleavage of β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyluronate bonds of gellan backbone releasing tetrasaccharides containing a 4-deoxy-4,5-unsaturated D-glucopyranosyluronic acid at the non-reducing end. The tetrasaccharide produced from deacetylated gellan is β-D-4-deoxy-Δ4-GlcAp-(1→4)-β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-β-D-Glcp.
Systematic name: gellan β-D-glucopyranosyl-(1→4)-D-glucopyranosyluronate lyase
Comments: The enzyme is highly specific to gellan, especially deacetylated gellan.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Hashimoto, W., Maesaka, K., Sato, N., Kimura, S., Yamamoto, K., Kumagai, H. and Murata, K. Microbial system for polysaccharide depolymerization: enzymatic route for gellan depolymerization by Bacillus sp. GL1. Arch. Biochem. Biophys. 339 (1997) 17–23. [DOI] [PMID: 9056228]
2.  Hashimoto, W., Sato, N., Kimura, S. and Murata, K. Polysaccharide lyase: molecular cloning of gellan lyase gene and formation of the lyase from a huge precursor protein in Bacillus sp. GL1. Arch. Biochem. Biophys. 354 (1998) 31–39. [DOI] [PMID: 9633595]
3.  Miyake, O., Kobayashi, E., Nankai, H., Hashimoto, W., Mikami, B. and Murata, K. Posttranslational processing of polysaccharide lyase: maturation route for gellan lyase in Bacillus sp. GL1. Arch. Biochem. Biophys. 422 (2004) 211–220. [DOI] [PMID: 14759609]
[EC 4.2.2.25 created 2011]
 
 
EC 4.2.2.26     
Accepted name: oligo-alginate lyase
Reaction: Cleavage of poly(4-deoxy-α-L-erythro-hexopyranuronoside) oligosaccharides with 4-deoxy-α-L-erythro-hex-4-enopyranuronosyl groups at their non-reducing ends into 4-deoxy-α-L-erythro-hex-4-enopyranuronate monosaccharides.
Other name(s): aly (gene name) (ambiguous); oalS17 (gene name); oligoalginate lyase; exo-oligoalginate lyase
Systematic name: alginate oligosaccharide 4-deoxy-α-L-erythro-hex-4-enopyranuronate-(1→4)-hexananopyranuronate lyase
Comments: The enzyme degrades unsaturated oligosaccharides produced by the action of alginate lyases (EC 4.2.2.3 and EC 4.2.2.11) on alginate, by repeatedly removing the unsaturated residue from the non-reducing end until only unsaturated monosaccharides are left. The enzyme catalyses a β-elimination reaction, generating a new unsaturated non-reducing end after removal of the pre-existing one.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB
References:
1.  Hashimoto, W., Miyake, O., Momma, K., Kawai, S. and Murata, K. Molecular identification of oligoalginate lyase of Sphingomonas sp. strain A1 as one of the enzymes required for complete depolymerization of alginate. J. Bacteriol. 182 (2000) 4572–4577. [DOI] [PMID: 10913091]
2.  Kim, H.T., Chung, J.H., Wang, D., Lee, J., Woo, H.C., Choi, I.G. and Kim, K.H. Depolymerization of alginate into a monomeric sugar acid using Alg17C, an exo-oligoalginate lyase cloned from Saccharophagus degradans 2-40. Appl. Microbiol. Biotechnol. 93 (2012) 2233–2239. [DOI] [PMID: 22281843]
3.  Jagtap, S.S., Hehemann, J.H., Polz, M.F., Lee, J.K. and Zhao, H. Comparative biochemical characterization of three exolytic oligoalginate lyases from Vibrio splendidus reveals complementary substrate scope, temperature, and pH adaptations. Appl. Environ. Microbiol. 80 (2014) 4207–4214. [DOI] [PMID: 24795372]
4.  Wang, L., Li, S., Yu, W. and Gong, Q. Cloning, overexpression and characterization of a new oligoalginate lyase from a marine bacterium, Shewanella sp. Biotechnol. Lett. 37 (2015) 665–671. [DOI] [PMID: 25335746]
[EC 4.2.2.26 created 2015]
 
 
EC 4.2.2.27     
Accepted name: pectin monosaccharide-lyase
Reaction: (1,4-α-D-galacturonosyl methyl ester)n = (1,4-α-D-galacturonosyl methyl ester)n-1 + 4-deoxy-6-O-methyl-L-threo-hex-4-enopyranuronate
Other name(s): exo-pectin lyase; PLIII
Systematic name: poly(1,4-α-D-galacturonosyl methyl ester) non-reducing-end-monosaccharide-lyase
Comments: The enzyme, isolated from the fungus Aspergillus giganteus, acts on the non-reducing end of methyl-esterified polygalacturonan, releasing either 4-deoxy--L-threo-hex-4-enopyranuronate or 4-deoxy-6-O-methyl-L-threo-hex-4-enopyranuronate. The enzyme is stimulated by divalent cations, with Co2+ having the strongest effect. It is able to act on substrates as short as a disaccharide, and was active on substrates with degrees of methyl esterification ranging between 34% and 90%.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Pedrolli, D.B. and Carmona, E.C. Purification and characterization of a unique pectin lyase from Aspergillus giganteus able to release unsaturated monogalacturonate during pectin degradation. Enzyme Res. 2014:353915 (2014). [PMID: 25610636]
[EC 4.2.2.27 created 2020]
 
 
EC 4.2.2.28     
Accepted name: α-L-rhamnosyl-(1→4)-D-glucuronate lyase
Reaction: α-L-rhamnosyl-(1→4)-D-glucuronate = L-rhamnopyranose + 4-deoxy-L-threo-hex-4-enopyranuronate
Other name(s): L-rhamnose-α-1,4-D-glucuronate lyase; FoRham (gene name)
Systematic name: α-L-rhamnosyl-(1→4)-D-glucuronate lyase
Comments: The enzyme, characterized from the phytopathogenic fungus Fusarium oxysporum, removes the rhamnosyl residue from α-L-rhamnosyl-(1→4)-D-glucuronate or (with lower activity) from oligosaccharides that contain this motif at the non-reducing end, leaving an unsaturated glucuronate residue. Among its natural substrates is the type II arabinogalactan component of gum arabic.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Kondo, T., Kichijo, M., Maruta, A., Nakaya, M., Takenaka, S., Arakawa, T., Fushinobu, S. and Sakamoto, T. Structural and functional analysis of gum arabic L-rhamnose-α-1,4-D-glucuronate lyase establishes a novel polysaccharide lyase family. J. Biol. Chem. 297:101001 (2021). [DOI] [PMID: 34303708]
[EC 4.2.2.28 created 2022, modified 2024]
 
 
EC 4.2.2.29     
Accepted name: peptidoglycan lytic transglycosylase
Reaction: a peptidoglycan chain = a peptidoglycan chain with N-acetyl-1,6-anhydromuramyl-(peptide) at the reducing end + a peptidoglycan chain with N-acetylglucosamine at the non-reducing end
Other name(s): lytic murein transglycosylase; endolytic murein transglycosylase; lytic transglycosylase; endolytic transglycosylase; MtlA; MltB; MltC; MltD; MltE; MltF; MltG; Slt; RlpA; SleB; SpoIID
Systematic name: peptidoglycan N-acetylmuramate—N-acetyl-β-D-glucosamine lyase
Comments: A group of bacterial enzymes that catalyse the non-hydrolytic cleavage of peptidoglycan (PG). The enzymes fragment the polysaccharide chain at the β-1,4-glycosidic bond between N-acetylmuramic acid and N-acetylglucosamine residues by an intramolecular cyclization of the N-acetylmuramyl moiety to yield a 1,6-anhydro-N-acetyl-β-D-muramyl product. Includes endolytic transglycosylase activity that fragments the glycan chain internally and exolytic transgylcosylase activity that cleaves a terminal disaccharide from the end of the glycan strand. The MtlG enzyme of Gram-negative bacteria may function to regulate glycan strand length within the PG polymer.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB
References:
1.  Holtje, J.V., Mirelman, D., Sharon, N. and Schwarz, U. Novel type of murein transglycosylase in Escherichia coli. J. Bacteriol. 124 (1975) 1067–1076. [DOI] [PMID: 357]
2.  Yunck, R., Cho, H. and Bernhardt, T.G. Identification of MltG as a potential terminase for peptidoglycan polymerization in bacteria. Mol. Microbiol. 99 (2016) 700–718. [DOI] [PMID: 26507882]
3.  Dik, D.A., Marous, D.R., Fisher, J.F. and Mobashery, S. Lytic transglycosylases: concinnity in concision of the bacterial cell wall. Crit. Rev. Biochem. Mol. Biol. 52 (2017) 503–542. [DOI] [PMID: 28644060]
[EC 4.2.2.29 created 2023]
 
 
EC 4.2.2.30     
Accepted name: inulin endo fructotransferase (reducing-end-DFA-III-forming)
Reaction: Cleaves the internal bond of (2→1)-β-D-fructan (inulin) chain and produces α-D-fructofuranose β-D-fructofuranose 1,2′:2,3′-dianhydride (DFA III) at the reducing end.
Glossary: DFA = difructose dianhydride
Other name(s): endo-type inulin fructotransferase
Systematic name: endo (2→1)-β-D-fructan lyase (α-D-fructofuranose-β-D-fructofuranose-1,2′:2,3′-dianhydride-linked linear (2→1)-β-D-fructofuranoside-forming)
Comments: The enzyme from Bacteroides caccae is a heterodimer composed of large and small subunits, both having a glycoside hydrolase family 91 domain. It cleaves inulin so that one of the products retains the glucosyl residue at the reducing end, while a DFA-III disaccharide is formed at the reducing end of the second product. Unlike this enzyme, inulin fructotransferase (DFA-III-forming) (EC 4.2.2.18) catalyses an exo-type reaction and releases free DFA III.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Rakoff-Nahoum, S., Foster, K.R. and Comstock, L.E. The evolution of cooperation within the gut microbiota. Nature 533 (2016) 255–259. [DOI] [PMID: 27111508]
2.  Ishiwata, A., Shite, Y., Kitahara, K., Tanaka, K., Ito, Y. and Fujita, K. Structural analysis of (2→1)-β-D-fructofuranosides linked to a terminal difructose dianhydride III produced by Bacteroides endo-type inulin fructotransferase. Int. J. Biol. Macromol. 310:143064 (2025). [DOI] [PMID: 40220837]
[EC 4.2.2.30 created 2025]
 
 
EC 4.2.3.1     
Accepted name: threonine synthase
Reaction: O-phospho-L-homoserine + H2O = L-threonine + phosphate
For diagram of threonine biosynthesis, click here
Other name(s): threonine synthetase; O-phospho-L-homoserine phospho-lyase (adding water)
Systematic name: O-phospho-L-homoserine phosphate-lyase (adding water; L-threonine-forming)
Comments: A pyridoxal-phosphate protein.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9023-97-6
References:
1.  Flavin, M. and Slaughter, C. Purification and properties of threonine synthetase of Neurospora. J. Biol. Chem. 235 (1960) 1103–1108. [PMID: 13823379]
[EC 4.2.3.1 created 1961 as EC 4.2.99.2, transferred 2000 to EC 4.2.3.1]
 
 
EC 4.2.3.2     
Accepted name: ethanolamine-phosphate phospho-lyase
Reaction: ethanolamine phosphate + H2O = acetaldehyde + NH3 + phosphate
Other name(s): O-phosphoethanolamine-phospholyase; amino alcohol O-phosphate phospholyase; O-phosphorylethanol-amine phospho-lyase; ethanolamine-phosphate phospho-lyase (deaminating)
Systematic name: ethanolamine-phosphate phosphate-lyase (deaminating; acetaldehyde-forming)
Comments: A pyridoxal-phosphate protein. Also acts on D(or L)-1-aminopropan-2-ol O-phosphate.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 37290-88-3
References:
1.  Fleshood, H.L. and Pitot, H.C. The metabolism of O-phosphorylethanolamine in animal tissues. I. O-Phosphorylethanolamine phospho-lyase: partial purification and characterization. J. Biol. Chem. 245 (1970) 4414–4420. [PMID: 5498429]
2.  Jones, A., Faulkner, A. and Turner, J.M. Microbial metabolism of amino alcohols. Metabolism of ethanolamine and 1-aminopropan-2-ol in species of Erwinia and the roles of amino alcohol kinase and amino alcohol o-phosphate phospho-lyase in aldehyde formation. Biochem. J. 134 (1973) 959–968. [PMID: 4357716]
[EC 4.2.3.2 created 1972 as EC 4.2.99.7, transferred 2000 to EC 4.2.3.2]
 
 
EC 4.2.3.3     
Accepted name: methylglyoxal synthase
Reaction: glycerone phosphate = 2-oxopropanal + phosphate
Glossary: glycerone phosphate = dihydroxyacetone phosphate = 3-hydroxy-2-oxopropyl phosphate
2-oxopropanal = methylglyoxal
Other name(s): methylglyoxal synthetase; glycerone-phosphate phospho-lyase
Systematic name: glycerone-phosphate phosphate-lyase (methylglyoxal-forming)
Comments: Does not act on D-glyceraldehyde 3-phosphate.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 37279-01-9
References:
1.  Cooper, R.A. and Anderson, A. The formation and catabolism of methylglyoxal during glycolysis in Escherichia coli. FEBS Lett. 11 (1970) 273–276. [DOI] [PMID: 11945504]
2.  Hopper, D.J. and Cooper, R.A. The regulation of Escherichia coli methylglyoxal synthase; a new control site in glycolysis? FEBS Lett. 13 (1971) 213–216. [DOI] [PMID: 11945670]
3.  Ray, S. and Ray, M. Isolation of methylglyoxal synthase from goat liver. J. Biol. Chem. 256 (1981) 6230–6233. [PMID: 7240200]
[EC 4.2.3.3 created 1972 as EC 4.2.99.11, transferred 2000 to EC 4.2.3.3]
 
 
EC 4.2.3.4     
Accepted name: 3-dehydroquinate synthase
Reaction: 3-deoxy-D-arabino-hept-2-ulosonate 7-phosphate = 3-dehydroquinate + phosphate
For diagram of shikimate and chorismate biosynthesis, click here and for mechanism of reaction, click here
Glossary: quinate = (1R,3R,4R,5R)-1,3,4,5-tetrahydroxycyclohexanecarboxylic acid and is a cyclitol carboxylate
The numbering system used for the 3-dehydroquinate is that of the recommendations on cyclitols, sections I-8 and I-9: and is shown in the reaction diagram). The use of the term ’5-dehydroquinate’ for this compound is based on an earlier system of numbering.
Other name(s): 5-dehydroquinate synthase; 5-dehydroquinic acid synthetase; dehydroquinate synthase; 3-dehydroquinate synthetase; 3-deoxy-arabino-heptulosonate-7-phosphate phosphate-lyase (cyclizing); 3-deoxy-arabino-heptulonate-7-phosphate phosphate-lyase (cyclizing); 3-deoxy-arabino-heptulonate-7-phosphate phosphate-lyase (cyclizing; 3-dehydroquinate-forming)
Systematic name: 3-deoxy-D-arabino-hept-2-ulosonate-7-phosphate phosphate-lyase (cyclizing; 3-dehydroquinate-forming)
Comments: Requires Co2+ and bound NAD+. The hydrogen atoms on C-7 of the substrate are retained on C-2 of the product.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 37211-77-1
References:
1.  Rotenberg, S.L. and Sprinson, D.B. Mechanism and stereochemistry of 5-dehydroquinate synthetase. Proc. Natl. Acad. Sci. USA 67 (1970) 1669–1672. [DOI] [PMID: 5275368]
2.  Srinivasan, P.R., Rothschild, J. and Sprinson, D.B. The enzymic conversion of 3-deoxy-D-arabino-heptulosonic acid 7-phosphate to 5-dehydroquinate. J. Biol. Chem. 238 (1963) 3176–3182. [PMID: 14085358]
3.  Bender, S.L., Mehdi, S. and Knowles, J.R. Dehydroquinate synthase: the role of divalent metal cations and of nicotinamide adenine dinucleotide in catalysis. Biochemistry 28 (1989) 7555–7560. [PMID: 2514789]
4.  Carpenter, E.P., Hawkins, A.R., Frost, J.W. and Brown, K.A. Structure of dehydroquinate synthase reveals an active site capable of multistep catalysis. Nature 394 (1998) 299–302. [DOI] [PMID: 9685163]
[EC 4.2.3.4 created 1978 as EC 4.6.1.3, transferred 2000 to EC 4.2.3.4, modified 2002]
 
 
EC 4.2.3.5     
Accepted name: chorismate synthase
Reaction: 5-O-(1-carboxyvinyl)-3-phosphoshikimate = chorismate + phosphate
For diagram of shikimate and chorismate biosynthesis, click here and for mechanism of reaction, click here
Other name(s): 5-O-(1-carboxyvinyl)-3-phosphoshikimate phosphate-lyase
Systematic name: 5-O-(1-carboxyvinyl)-3-phosphoshikimate phosphate-lyase (chorismate-forming)
Comments: Requires FMN. The reaction goes via a radical mechanism that involves reduced FMN and its semiquinone (FMNH·). Shikimate is numbered so that the double-bond is between C-1 and C-2, but some earlier papers numbered the ring in the reverse direction.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 9077-07-0
References:
1.  Gaertner, F.H. and Cole, K.W. Properties of chorismate synthase in Neurospora crassa. J. Biol. Chem. 248 (1973) 4602–4609. [PMID: 4146266]
2.  Morell, H., Clark, M.J., Knowles, P.F. and Sprinson, D.B. The enzymic synthesis of chorismic and prephenic acids from 3-enolpyruvylshikimic acid 5-phosphate. J. Biol. Chem. 242 (1967) 82–90. [PMID: 4289188]
3.  Welch, G.R., Cole, K.W. and Gaertner, F.H. Chorismate synthase of Neurospora crassa: a flavoprotein. Arch. Biochem. Biophys. 165 (1974) 505–518. [DOI] [PMID: 4155270]
4.  Bornemann, S., Lowe, D.J. and Thorneley, R.N. The transient kinetics of Escherichia coli chorismate synthase: substrate consumption, product formation, phosphate dissociation, and characterization of a flavin intermediate. Biochemistry 35 (1996) 9907–9916. [DOI] [PMID: 8703965]
5.  Bornemann, S., Theoclitou, M.E., Brune, M., Webb, M.R., Thorneley, R.N. and Abell, C. A secondary β deuterium kinetic isotope effect in the chorismate synthase reaction. Bioorg. Chem. 28 (2000) 191–204. [DOI] [PMID: 11034781]
6.  Osborne, A., Thorneley, R.N., Abell, C. and Bornemann, S. Studies with substrate and cofactor analogues provide evidence for a radical mechanism in the chorismate synthase reaction. J. Biol. Chem. 275 (2000) 35825–35830. [DOI] [PMID: 10956653]
[EC 4.2.3.5 created 1978 as EC 4.6.1.4, modified 1983, transferred 2000 to EC 4.2.3.5, modified 2002]
 
 
EC 4.2.3.6     
Accepted name: trichodiene synthase
Reaction: (2E,6E)-farnesyl diphosphate = trichodiene + diphosphate
For diagram of biosynthesis of bicyclic sesquiterpenoids derived from bisabolyl cation, click here and for diagram of trichodiene and (–)-α-cuprenene biosynthesis, click here
Other name(s): trichodiene synthetase; sesquiterpene cyclase; trans,trans-farnesyl-diphosphate sesquiterpenoid-lyase
Systematic name: (2E,6E)-farnesyl-diphosphate diphosphate-lyase (cyclizing, trichodiene-forming)
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 101915-76-8
References:
1.  Hohn, T.M. and Vanmiddlesworth, F. Purification and characterization of the sesquiterpene cyclase trichodiene synthetase from Fusarium sporotrichioides. Arch. Biochem. Biophys. 251 (1986) 756–761. [DOI] [PMID: 3800398]
2.  Hohn, T.M. and Beremand, P.D. Isolation and nucleotide sequence of a sesquiterpene cyclase gene from the trichothecene-producing fungus Fusarium sporotrichioides. Gene 79 (1989) 131–138. [DOI] [PMID: 2777086]
3.  Rynkiewicz, M.J., Cane, D.E. and Christianson, D.W. Structure of trichodiene synthase from Fusarium sporotrichioides provides mechanistic inferences on the terpene cyclization cascade. Proc. Natl. Acad. Sci. USA 98 (2001) 13543–13548. [DOI] [PMID: 11698643]
[EC 4.2.3.6 created 1989 as EC 4.1.99.6, transferred 2000 to EC 4.2.3.6]
 
 
EC 4.2.3.7     
Accepted name: pentalenene synthase
Reaction: (2E,6E)-farnesyl diphosphate = pentalenene + diphosphate
For diagram of sesquiterpenoid biosynthesis based on humulene, click here
Glossary: pentalenene = (1R,8aR)-1,4,7,7-tetramethyl-1,2,3,3a,5a,6,7,8-octahydrocyclopenta[c]pentalene
Other name(s): pentalenene synthetase
Systematic name: (2E,6E)-farnesyl-diphosphate diphosphate-lyase (cyclizing, pentalenene-forming)
Comments: Isolated from Streptomyces avermitilis. The enzyme is involved in the biosynthesis of pentalenolactone and related antibiotics. The 9si hydrogen of farnesyl diphosphate undergoes a 1,2-hydride shift where it becomes the 1α hydrogen of pentalenene.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 90597-46-9
References:
1.  Cane, D.E. Cell-free studies of monoterpene and sesquiterpene biosynthesis. Biochem. Soc. Trans. 11 (1983) 510–515. [PMID: 6642060]
2.  Cane, D.E. and Tillman, A.M. Pentalenene biosynthesis and the enzymic cyclization of farnesyl pyrophosphate. J. Am. Chem. Soc. 105 (1983) 122–124.
3.  Cane, D.E., Sohng, J.K., Lamberson, C.R., Rudnicki, S.M., Wu, Z., Lloyd, M.D., Oliver, J.S. and Hubbard, B.R. Pentalenene synthase. Purification, molecular cloning, sequencing, and high-level expression in Escherichia coli of a terpenoid cyclase from Streptomyces UC5319. Biochemistry 33 (1994) 5846–5857. [PMID: 8180213]
4.  Cane, D.E., Abell, C., Harrison, P.H., Hubbard, B.R., Kane, C.T., Lattman, R., Oliver, J.S. and Weiner, S.W. Terpenoid biosynthesis and the stereochemistry of enzyme-catalysed allylic addition-elimination reactions. Philos. Trans. R. Soc. Lond. B Biol. Sci. 332 (1991) 123–129. [DOI] [PMID: 1678531]
5.  Lesburg, C.A., Zhai, G., Cane, D.E. and Christianson, D.W. Crystal structure of pentalenene synthase: mechanistic insights on terpenoid cyclization reactions in biology. Science 277 (1997) 1820–1824. [DOI] [PMID: 9295272]
6.  Zu, L., Xu, M., Lodewyk, M.W., Cane, D.E., Peters, R.J. and Tantillo, D.J. Effect of isotopically sensitive branching on product distribution for pentalenene synthase: support for a mechanism predicted by quantum chemistry. J. Am. Chem. Soc. 134 (2012) 11369–11371. [DOI] [PMID: 22738258]
[EC 4.2.3.7 created 1989 as EC 4.6.1.5, transferred 2000 to EC 4.2.3.7]
 
 
EC 4.2.3.8     
Accepted name: casbene synthase
Reaction: geranylgeranyl diphosphate = casbene + diphosphate
For diagram of cembrene and related diterpenoids, click here
Other name(s): casbene synthetase; geranylgeranyl-diphosphate diphosphate-lyase (cyclizing)
Systematic name: geranylgeranyl-diphosphate diphosphate-lyase (cyclizing, casbene-forming)
Comments: The enzyme from castor bean (Ricinus communis) produces the antifungal diterpene casbene.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, CAS registry number: 69106-45-2
References:
1.  Moesta, P. and West, C.A. Casbene synthetase: regulation of phytoalexin biosynthesis in Ricinus communis L. seedlings. Purification of casbene synthetase and regulation of its biosynthesis during elicitation. Arch. Biochem. Biophys. 238 (1985) 325–333. [DOI] [PMID: 3985625]
2.  Mau, C.J. and West, C.A. Cloning of casbene synthase cDNA: evidence for conserved structural features among terpenoid cyclases in plants. Proc. Natl. Acad. Sci. USA 91 (1994) 8497–8501. [DOI] [PMID: 8078910]
[EC 4.2.3.8 created 1989 as EC 4.6.1.7, transferred 2000 to EC 4.2.3.8, modified 2024]
 
 
EC 4.2.3.9     
Accepted name: aristolochene synthase
Reaction: (2E,6E)-farnesyl diphosphate = aristolochene + diphosphate
For diagram of eremophilane and spirovetivane sesquiterpenoid biosynthesis, click here
Other name(s): sesquiterpene cyclase; trans,trans-farnesyl diphosphate aristolochene-lyase; trans,trans-farnesyl-diphosphate diphosphate-lyase (cyclizing, aristolochene-forming)
Systematic name: (2E,6E)-farnesyl-diphosphate diphosphate-lyase (cyclizing, aristolochene-forming)
Comments: The initial internal cyclization produces the monocyclic intermediate germacrene A; further cyclization and methyl transfer converts the intermediate into aristolochene. While in some species germacrene A remains as an enzyme-bound intermediate, it has been shown to be a minor product of the reaction in Penicillium roqueforti [5] (see also EC 4.2.3.23, germacrene-A synthase). The enzyme from Penicillium roqueforti requires Mg2+. Mn2+ can partially substitute, at low concentrations. Aristolochene is the likely parent compound for a number of sesquiterpenes produced by filamentous fungi.
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, PDB, CAS registry number: 94185-89-4
References:
1.  Cane, D.E., Prabhakaran, P.C., Oliver, J.S. and McIlwaine, D.B. Aristolochene biosynthesis. Stereochemistry of the deprotonation steps in the enzymatic cyclization of farnesyl pyrophosphate. J. Am. Chem. Soc. 112 (1990) 3209–3210.
2.  Cane, D.E., Prabhakaran, P.C., Salaski, E.J., Harrison, P.M.H., Noguchi, H. and Rawlings, B.J. Aristolochene biosynthesis and enzymatic cyclization of farnesyl pyrophosphate. J. Am. Chem. Soc. 111 (1989) 8914–8916.
3.  Hohn, T.M. and Plattner, R.D. Purification and characterization of the sesquiterpene cyclase aristolochene synthase from Penicillium roqueforti. Arch. Biochem. Biophys. 272 (1989) 137–143. [DOI] [PMID: 2544140]
4.  Proctor, R.H. and Hohn, T.M. Aristolochene synthase. Isolation, characterization, and bacterial expression of a sesquiterpenoid biosynthetic gene (Ari1) from Penicillium roqueforti. J. Biol. Chem. 268 (1993) 4543–4548. [PMID: 8440737]
5.  Calvert, M.J., Ashton, P.R. and Allemann, R.K. Germacrene A is a product of the aristolochene synthase-mediated conversion of farnesylpyrophosphate to aristolochene. J. Am. Chem. Soc. 124 (2002) 11636–11641. [DOI] [PMID: 12296728]
[EC 4.2.3.9 created 1992 as EC 2.5.1.40, transferred 1999 to EC 4.1.99.7, transferred 2000 to EC 4.2.3.9, modified 2006]
 
 
EC 4.2.3.10     
Accepted name: (-)-endo-fenchol synthase
Reaction: geranyl diphosphate + H2O = (-)-endo-fenchol + diphosphate
For diagram of monoterpenoid biosynthesis, click here
Other name(s): (-)-endo-fenchol cyclase; geranyl pyrophosphate:(-)-endo-fenchol cyclase
Systematic name: geranyl-diphosphate diphosphate-lyase [cyclizing, (-)-endo-fenchol-forming]
Comments: (3R)-Linalyl diphosphate is an intermediate in the reaction
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 117758-41-5
References:
1.  Croteau, R., Miyazaki, J.H. and Wheeler, C.J. Monoterpene biosynthesis: mechanistic evaluation of the geranyl pyrophosphate:(-)-endo-fenchol cyclase from fennel (Foeniculum vulgare). Arch. Biochem. Biophys. 269 (1989) 507–516. [DOI] [PMID: 2919880]
2.  Croteau, R., Satterwhite, D.M., Wheeler, C.J. and Felton, N.M. Biosynthesis of monoterpenes. Stereochemistry of the enzymatic cyclization of geranyl pyrophosphate to (-)-endo-fenchol. J. Biol. Chem. 263 (1988) 15449–15453. [PMID: 3170591]
[EC 4.2.3.10 created 1992 as EC 4.6.1.8, transferred 2000 to EC 4.2.3.10]
 
 
EC 4.2.3.11     
Accepted name: sabinene-hydrate synthase
Reaction: geranyl diphosphate + H2O = sabinene hydrate + diphosphate
For diagram of monoterpenoid biosynthesis, click here
Other name(s): sabinene hydrate cyclase
Systematic name: geranyl-diphosphate diphosphate-lyase (cyclizing, sabinene-hydrate-forming)
Comments: Both cis- and trans- isomers of sabinene hydrate are formed. (3R)-Linalyl diphosphate is an intermediate in the reaction
Links to other databases: BRENDA, EXPASY, Gene, KEGG, MetaCyc, CAS registry number: 117164-95-1
References:
1.  Hallahan, T.W. and Croteau, R. Monoterpene biosynthesis: demonstration of a geranyl pyrophosphate:sabinene hydrate cyclase in soluble enzyme preparations from sweet marjoram (Majorana hortensis). Arch. Biochem. Biophys. 264 (1988) 618–631. [DOI] [PMID: 3401015]
2.  Hallahan, T.W. and Croteau, R. Monoterpene biosynthesis: mechanism and stereochemistry of the enzymatic cyclization of geranyl pyrophosphate to (+)-cis- and (+)-trans-sabinene hydrate. Arch. Biochem. Biophys. 269 (1989) 313–326. [DOI] [PMID: 2916845]
[EC 4.2.3.11 created 1992 as EC 4.6.1.9, transferred 2000 to EC 4.2.3.11]
 
 


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