EC	3.2.1.172
Accepted name:	unsaturated rhamnogalacturonyl hydrolase
Reaction:	2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-rhamnopyranose + H2O = 5-dehydro-4-deoxy-D-glucuronate + L-rhamnopyranose
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 5-dehydro-4-deoxy-D-glucuronate = (4S,5R)-4,5-dihydroxy-2,6-dioxohexanoate
Other name(s):	YteR; YesR
Systematic name:	2-O-(4-deoxy-β-L-threo-hex-4-enopyranuronosyl)-α-L-rhamnopyranose hydrolase
Comments:	The enzyme is part of the degradation system for rhamnogalacturonan I in Bacillus subtilis strain 168.
References:	1.  Itoh, T., Ochiai, A., Mikami, B., Hashimoto, W. and Murata, K. A novel glycoside hydrolase family 105: the structure of family 105 unsaturated rhamnogalacturonyl hydrolase complexed with a disaccharide in comparison with family 88 enzyme complexed with the disaccharide. J. Mol. Biol. 360 (2006) 573–585. [PMID: 16781735] 2.  Zhang, R., Minh, T., Lezondra, L., Korolev, S., Moy, S.F., Collart, F. and Joachimiak, A. 1.6 Å crystal structure of YteR protein from Bacillus subtilis, a predicted lyase. Proteins 60 (2005) 561–565. [PMID: 15906318] 3.  Itoh, T., Ochiai, A., Mikami, B., Hashimoto, W. and Murata, K. Structure of unsaturated rhamnogalacturonyl hydrolase complexed with substrate. Biochem. Biophys. Res. Commun. 347 (2006) 1021–1029. [PMID: 16870154]
[EC 3.2.1.172 created 2011, modified 2012]
EC	3.2.1.179
Accepted name:	gellan tetrasaccharide unsaturated glucuronosyl hydrolase
Reaction:	β-D-4-deoxy-Δ4-GlcAp-(1→4)-β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-D-Glcp + H2O = 5-dehydro-4-deoxy-D-glucuronate + β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-D-Glcp
Glossary:	5-dehydro-4-deoxy-D-glucuronate = (4S,5R)-4,5-dihydroxy-2,6-dioxohexanoate β-D-4-deoxy-Δ4-GlcAp-(1→3)-D-GalNAc = 3-(4-deoxy-β-D-gluc-4-enuronosyl)-N-acetyl-D-galactosamine = 3-(4-deoxy-α-L-threo-hex-4-enopyranosyluronic acid)-2-acetamido-2-deoxy-D-galactose
Other name(s):	UGL (ambiguous); unsaturated glucuronyl hydrolase (ambiguous); gellan tetrasaccharide unsaturated glucuronyl hydrolase
Systematic name:	β-D-4-deoxy-Δ4-GlcAp-(1→4)-β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-D-Glcp β-D-4-deoxy-Δ4-GlcAp hydrolase
Comments:	The enzyme releases 4-deoxy-4(5)-unsaturated D-glucuronic acid from oligosaccharides produced by polysaccharide lyases, e.g. the tetrasaccharide β-D-4-deoxy-Δ4-GlcAp-(1→4)-β-D-Glcp-(1→4)-α-L-Rhap-(1→3)-D-Glcp produced by EC 4.2.2.25, gellan lyase. The enzyme can also hydrolyse unsaturated chondroitin and hyaluronate disaccharides (β-D-4-deoxy-Δ4-GlcAp-(1→3)-D-GalNAc, β-D-4-deoxy-Δ4-GlcAp-(1→3)-D-GalNAc6S, β-D-4-deoxy-Δ4-GlcAp2S-(1→3)-D-GalNAc, β-D-4-deoxy-Δ4-GlcAp-(1→3)-D-GlcNAc), preferring the unsulfated disaccharides to the sulfated disaccharides.
References:	1.  Itoh, T., Akao, S., Hashimoto, W., Mikami, B. and Murata, K. Crystal structure of unsaturated glucuronyl hydrolase, responsible for the degradation of glycosaminoglycan, from Bacillus sp. GL1 at 1.8 Å resolution. J. Biol. Chem. 279 (2004) 31804–31812. [PMID: 15148314] 2.  Hashimoto, W., Kobayashi, E., Nankai, H., Sato, N., Miya, T., Kawai, S. and Murata, K. Unsaturated glucuronyl hydrolase of Bacillus sp. GL1: novel enzyme prerequisite for metabolism of unsaturated oligosaccharides produced by polysaccharide lyases. Arch. Biochem. Biophys. 368 (1999) 367–374. [PMID: 10441389] 3.  Itoh, T., Hashimoto, W., Mikami, B. and Murata, K. Substrate recognition by unsaturated glucuronyl hydrolase from Bacillus sp. GL1. Biochem. Biophys. Res. Commun. 344 (2006) 253–262. [PMID: 16630576]
[EC 3.2.1.179 created 2011, modified 2016]
EC	3.2.1.180
Accepted name:	unsaturated chondroitin disaccharide hydrolase
Reaction:	β-D-4-deoxy-Δ4-GlcAp-(1→3)-β-D-GalNAc6S + H2O = 5-dehydro-4-deoxy-D-glucuronate + N-acetyl-β-D-galactosamine-6-O-sulfate
Glossary:	5-dehydro-4-deoxy-D-glucuronate = (4S,5R)-4,5-dihydroxy-2,6-dioxohexanoate
Other name(s):	UGL (ambiguous); unsaturated glucuronyl hydrolase (ambiguous)
Systematic name:	β-D-4-deoxy-Δ4-GlcAp-(1→3)-β-D-GalNAc6S hydrolase
Comments:	The enzyme releases 4-deoxy-4,5-didehydro D-glucuronic acid or 4-deoxy-4,5-didehydro L-iduronic acid from chondroitin disaccharides, hyaluronan disaccharides and heparin disaccharides and cleaves both glycosidic (1→3) and (1→4) bonds. It prefers the sulfated disaccharides to the unsulfated disaccharides.
References:	1.  Maruyama, Y., Nakamichi, Y., Itoh, T., Mikami, B., Hashimoto, W. and Murata, K. Substrate specificity of streptococcal unsaturated glucuronyl hydrolases for sulfated glycosaminoglycan. J. Biol. Chem. 284 (2009) 18059–18069. [PMID: 19416976] 2.  Nakamichi, Y., Maruyama, Y., Mikami, B., Hashimoto, W. and Murata, K. Structural determinants in streptococcal unsaturated glucuronyl hydrolase for recognition of glycosaminoglycan sulfate groups. J. Biol. Chem. 286 (2011) 6262–6271. [PMID: 21147778]
[EC 3.2.1.180 created 2011]
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.
References:	1.  Moran, F., Nasuno, S. and Starr, M.P. Oligogalacturonide trans-eliminase of Erwinia carotovora. Arch. Biochem. Biophys. 125 (1968) 734–741. [PMID: 5671040]
[EC 4.2.2.6 created 1972, modified 2010]
EC	5.3.1.17
Accepted name:	5-dehydro-4-deoxy-D-glucuronate isomerase
Reaction:	5-dehydro-4-deoxy-D-glucuronate = 3-deoxy-D-glycero-2,5-hexodiulosonate
Glossary:	5-dehydro-4-deoxy-D-glucuronate = (4S,5R)-4,5-dihydroxy-2,6-dioxohexanoate 3-deoxy-D-glycero-2,5-hexodiulosonate = (4S)-4,6-dihydroxy-2,5-dioxohexanoate
Other name(s):	4-deoxy-L-threo-5-hexulose uronate isomerase; 4-deoxy-L-threo-5-hexosulose-uronate ketol-isomerase; kduI (gene name)
Systematic name:	5-dehydro-4-deoxy-D-glucuronate aldose-ketose-isomerase
Comments:	The enzyme is involved in the degradation of polygalacturonate, a later stage in the degradation of pectin by many microorganisms.
References:	1.  Preiss, J. 4-Deoxy-L-threo-5-hexosulose uronic acid isomerase. Methods Enzymol. 9 (1966) 602–604. 2.  Condemine, G. and Robert-Baudouy, J. Analysis of an Erwinia chrysanthemi gene cluster involved in pectin degradation. Mol. Microbiol. 5 (1991) 2191–2202. [PMID: 1766386] 3.  Dunten, P., Jaffe, H. and Aksamit, R.R. Crystallization of 5-keto-4-deoxyuronate isomerase from Escherichia coli. Acta Crystallogr. D Biol. Crystallogr. 54 (1998) 678–680. [PMID: 9761873] 4.  Crowther, R.L. and Georgiadis, M.M. The crystal structure of 5-keto-4-deoxyuronate isomerase from Escherichia coli. Proteins 61 (2005) 680–684. [PMID: 16152643]
[EC 5.3.1.17 created 1972, modified 2012]