The Enzyme Database

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EC 2.1.1.13     
Accepted name: methionine synthase
Reaction: 5-methyltetrahydrofolate + L-homocysteine = tetrahydrofolate + L-methionine
For diagram of reaction, click here
Other name(s): 5-methyltetrahydrofolate—homocysteine S-methyltransferase; 5-methyltetrahydrofolate—homocysteine transmethylase; N-methyltetrahydrofolate:L-homocysteine methyltransferase; N5-methyltetrahydrofolate methyltransferase; N5-methyltetrahydrofolate-homocysteine cobalamin methyltransferase; N5-methyltetrahydrofolic—homocysteine vitamin B12 transmethylase; B12 N5-methyltetrahydrofolate homocysteine methyltransferase; methyltetrahydrofolate—homocysteine vitamin B12 methyltransferase; tetrahydrofolate methyltransferase; tetrahydropteroylglutamate methyltransferase; tetrahydropteroylglutamic methyltransferase; vitamin B12 methyltransferase; cobalamin-dependent methionine synthase; methionine synthase (cobalamin-dependent); MetH
Systematic name: 5-methyltetrahydrofolate:L-homocysteine S-methyltransferase
Comments: Contains zinc and cobamide. The enzyme becomes inactivated occasionally during its cycle by oxidation of Co(I) to Co(II). Reactivation by reductive methylation is catalysed by the enzyme itself, with S-adenosyl-L-methionine as the methyl donor and a reducing system. For the mammalian enzyme, the reducing system involves NADPH and EC 1.16.1.8, [methionine synthase] reductase. In bacteria, the reducing agent is flavodoxin, and no further catalyst is needed (the flavodoxin is kept in the reduced state by NADPH and EC 1.18.1.2, ferredoxin—NADP+ reductase). Acts on the monoglutamate as well as the triglutamate folate, in contrast with EC 2.1.1.14, 5-methyltetrahydropteroyltriglutamate—homocysteine S-methyltransferase, which acts only on the triglutamate.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 9033-23-2
References:
1.  Burton, E.G. and Sakami, W. The formation of methionine from the monoglutamate form of methyltetrahydrofolate by higher plants. Biochem. Biophys. Res. Commun. 36 (1969) 228–234. [DOI] [PMID: 5799642]
2.  Foster, M.A., Dilworth, M.J. and Woods, D.D. Cobalamin and the synthesis of methionine by Escherichia coli. Nature 201 (1964) 39–42. [PMID: 14085561]
3.  Guest, J.R., Friedman, S., Foster, M.A., Tejerina, G. and Woods, D.D. Transfer of the methyl group from N5-methyltetrahydrofolates to homocysteine in Escherichia coli. Biochem. J. 92 (1964) 497–504. [PMID: 5319972]
4.  Loughlin, R.E., Elford, H.L. and Buchanan, J.M. Enzymatic synthesis of the methyl group of methionine. VII. Isolation of a cobalamin-containing transmethylase (5-methyltetrahydro-folate-homocysteine) from mammalian liver. J. Biol. Chem. 239 (1964) 2888–2895. [PMID: 14216440]
5.  Taylor, R.T. Escherichia coli B N 5 -methyltetrahydrofolate-homocysteine cobalamin methyltransferase: gel-filtration behavior of apoenzyme and holoenzymes. Biochim. Biophys. Acta 242 (1971) 355–364. [DOI] [PMID: 4946148]
6.  Jarrett, J.T., Huang, S. and Matthews, R.G. Methionine synthase exists in two distinct conformations that differ in reactivity toward methyltetrahydrofolate, adenosylmethionine, and flavodoxin. Biochemistry 37 (1998) 5372–5382. [DOI] [PMID: 9548919]
7.  Peariso, K., Goulding, C.W., Huang, S., Matthews, R.G. and Penner-Hahn, J.E. Characterization of the zinc binding site in methionine synthase enzymes of Escherichia coli: The role of zinc in the methylation of homocysteine. J. Am. Chem. Soc. 120 (1998) 8410–8416.
8.  Hall, D.A., Jordan-Starck, T.C., Loo, R.O., Ludwig, M.L. and Matthews, R.G. Interaction of flavodoxin with cobalamin-dependent methionine synthase. Biochemistry 39 (2000) 10711–10719. [DOI] [PMID: 10978155]
9.  Bandarian, V., Pattridge, K.A., Lennon, B.W., Huddler, D.P., Matthews, R.G. and Ludwig, M.L. Domain alternation switches B12-dependent methionine synthase to the activation conformation. Nat. Struct. Biol. 9 (2002) 53–56. [DOI] [PMID: 11731805]
[EC 2.1.1.13 created 1972, modified 2003]
 
 
EC 2.1.1.130     
Accepted name: precorrin-2 C20-methyltransferase
Reaction: S-adenosyl-L-methionine + precorrin-2 = S-adenosyl-L-homocysteine + precorrin-3A
For diagram of corrin and siroheme biosynthesis (part 2), click here
Systematic name: S-adenosyl-L-methionine:precorrin-2 C20-methyltransferase
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 131554-12-6
References:
1.  Roessner, C.A., Warren, M.J., Santander, P.J., Atshaves, B.P., Ozaki, S., Stolowich, N.J., Iida, K., Scott, A.I. Expression of Salmonella typhimurium enzymes for cobinamide synthesis. Identification of the 11-methyl and 20-methyl transferases of corrin biosynthesis. FEBS Lett. 301 (1992) 73–78. [DOI] [PMID: 1451790]
2.  Roessner, C.A., Spencer, J.B., Ozaki, S., Min, C., Atshaves, B.P., Nayar, P., Anousis, N., Stolowich, N.J., Holderman, M.T., Scott, A.I. Overexpression in Escherichia coli of 12 vitamin B12 biosynthetic enzymes. Protein Extr. Purif. 6 (1995) 155–163. [DOI] [PMID: 7606163]
3.  Debussche, L., Thibaut, D., Cameron, B., Crouzet, J. and Blanche, F. Biosynthesis of the corrin macrocycle of coenzyme B12 in Pseudomonas denitrificans. J. Bacteriol. 175 (1993) 7430–7440. [DOI] [PMID: 8226690]
[EC 2.1.1.130 created 1999]
 
 
EC 2.1.1.131     
Accepted name: precorrin-3B C17-methyltransferase
Reaction: S-adenosyl-L-methionine + precorrin-3B = S-adenosyl-L-homocysteine + precorrin-4
For diagram of corrin biosynthesis (part 3), click here and for mechanism of reaction, click here
Other name(s): precorrin-3 methyltransferase; CobJ
Systematic name: S-adenosyl-L-methionine:precorrin-3B C17-methyltransferase
Comments: In the aerobic cobalamin biosythesis pathway, four enzymes are involved in the conversion of precorrin-3A to precorrin-6A. The first of the four steps is carried out by EC 1.14.13.83, precorrin-3B synthase (CobG), yielding precorrin-3B as the product. This is followed by three methylation reactions, which introduce a methyl group at C-17 (CobJ; EC 2.1.1.131), C-11 (CobM; EC 2.1.1.133) and C-1 (CobF; EC 2.1.1.152) of the macrocycle, giving rise to precorrin-4, precorrin-5 and precorrin-6A, respectively.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 152787-64-9
References:
1.  Scott, A.I., Roessner, C.A., Stolowich, N.J., Spencer, J.B., Min, C. and Ozaki, S.I. Biosynthesis of vitamin B12. Discovery of the enzymes for oxidative ring contraction and insertion of the fourth methyl group. FEBS Lett. 331 (1993) 105–108. [DOI] [PMID: 8405386]
2.  Debussche, L., Thibaut, D., Cameron, B., Crouzet, J. and Blanche, F. Biosynthesis of the corrin macrocycle of coenzyme B12 in Pseudomonas denitrificans. J. Bacteriol. 175 (1993) 7430–7440. [DOI] [PMID: 8226690]
[EC 2.1.1.131 created 1999]
 
 
EC 2.1.1.132     
Accepted name: precorrin-6B C5,15-methyltransferase (decarboxylating)
Reaction: 2 S-adenosyl-L-methionine + precorrin-6B = 2 S-adenosyl-L-homocysteine + precorrin-8X + CO2 (overall reaction)
(1a) S-adenosyl-L-methionine + precorrin-6B = S-adenosyl-L-homocysteine + precorrin-7 + CO2
(1b) S-adenosyl-L-methionine + precorrin-7 = S-adenosyl-L-homocysteine + precorrin-8X
For diagram of corrin biosynthesis (part 4), click here
Glossary: precorrin-6B = precorrin-6Y
Other name(s): precorrin-6 methyltransferase; precorrin-6Y methylase; precorrin-6Y C5,15-methyltransferase (decarboxylating); cobL (gene name)
Systematic name: S-adenosyl-L-methionine:1-precorrin-6B C5,15-methyltransferase (C-12-decarboxylating)
Comments: The enzyme, which participates in the aerobic adenosylcobalamin biosynthesis pathway, has S-adenosyl-L-methionine-dependent methyltransferase and decarboxylase activities. The enzyme is a fusion protein with two active sites; one catalyses the methylation at C15 and the decarboxylation, while the other catalyses the methylation at C5.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, PDB, CAS registry number: 162995-22-4
References:
1.  Blanche, F., Famechon, A., Thibaut, D., Debussche, L., Cameron, B., Crouzet, J. Biosynthesis of vitamin B12 in Pseudomonas denitrificans: the biosynthetic sequence from precorrin-6Y to precorrin-8X is catalyzed by the cobL gene product. J. Bacteriol. 174 (1992) 1050–1052. [DOI] [PMID: 1732195]
2.  Deery, E., Schroeder, S., Lawrence, A.D., Taylor, S.L., Seyedarabi, A., Waterman, J., Wilson, K.S., Brown, D., Geeves, M.A., Howard, M.J., Pickersgill, R.W. and Warren, M.J. An enzyme-trap approach allows isolation of intermediates in cobalamin biosynthesis. Nat. Chem. Biol. 8 (2012) 933–940. [DOI] [PMID: 23042036]
[EC 2.1.1.132 created 1999, modified 2013]
 
 
EC 2.1.1.133     
Accepted name: precorrin-4 C11-methyltransferase
Reaction: S-adenosyl-L-methionine + precorrin-4 = S-adenosyl-L-homocysteine + precorrin-5
For diagram of corrin biosynthesis (part 3), click here
Other name(s): precorrin-3 methylase; CobM
Systematic name: S-adenosyl-L-methionine:precorrin-4 C11 methyltransferase
Comments: In the aerobic cobalamin biosythesis pathway, four enzymes are involved in the conversion of precorrin-3A to precorrin-6A. The first of the four steps is carried out by EC 1.14.13.83, precorrin-3B synthase (CobG), yielding precorrin-3B as the product. This is followed by three methylation reactions, which introduce a methyl group at C-17 (CobJ; EC 2.1.1.131), C-11 (CobM; EC 2.1.1.133) and C-1 (CobF; EC 2.1.1.152) of the macrocycle, giving rise to precorrin-4, precorrin-5 and precorrin-6A, respectively.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 152787-65-0
References:
1.  Crouzet, J., Cameron, B., Cauchois, L., Rigault, S., Rouyez, M.C., Blanche, F. , Thibaut D., Debussche, L. Genetic and sequence analysis of an 8.7-kilobase Pseudomonas denitrificans fragment carrying eight genes involved in transformation of precorrin-2 to cobyrinic acid. J. Bacteriol. 172 (1990) 5980–5990. [DOI] [PMID: 2211521]
2.  Roth, J.R., Lawrence, J.G., Rubenfield, M., Kieffer-Higgins, S., Church, G.M. Characterization of the cobalamin (vitamin B12) biosynthetic genes of Salmonella typhimurium. J. Bacteriol. 175 (1993) 3303–3316. [DOI] [PMID: 8501034]
[EC 2.1.1.133 created 1999]
 
 
EC 2.1.1.134      
Deleted entry:  myo-inositol 6-O-methyltransferase. Now included with EC 2.1.1.129, inositol 4-methyltransferase
[EC 2.1.1.134 created 1999, deleted 2002]
 
 
EC 2.1.1.135      
Transferred entry: [methionine synthase]-cobalamin methyltransferase (cob(II)alamin reducing). Now EC 1.16.1.8, [methionine synthase] reductase
[EC 2.1.1.135 created 1999, deleted 2003]
 
 
EC 2.1.1.136     
Accepted name: chlorophenol O-methyltransferase
Reaction: S-adenosyl-L-methionine + trichlorophenol = S-adenosyl-L-homocysteine + trichloroanisole
Other name(s): halogenated phenol O-methyltransferase, trichlorophenol O-methyltransferase
Systematic name: S-adenosyl-L-methionine:trichlorophenol O-methyltransferase
Comments: The enzyme from Trichoderma virgatum, when cultured in the presence of halogenated phenol, also acts on a range of mono-, di- and trichlorophenols.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 196414-37-6
References:
1.  Kikuchi, T. and Oe, T. Halogenated phenol O-methyltransferase, its production and deodorization using the same. Patent JP9234062, 1997, Chem. Abstr., 127 (1994), 27468.
[EC 2.1.1.136 created 2000]
 
 
EC 2.1.1.137     
Accepted name: arsenite methyltransferase
Reaction: (1) S-adenosyl-L-methionine + arsenite = S-adenosyl-L-homocysteine + methylarsonate
(2) S-adenosyl-L-methionine + methylarsonite = S-adenosyl-L-homocysteine + dimethylarsinate
For diagram of arsenate catabolism, click here
Other name(s): S-adenosyl-L-methionine:arsenic(III) methyltransferase; S-adenosyl-L-methionine:methylarsonite As-methyltransferase; methylarsonite methyltransferase
Systematic name: S-adenosyl-L-methionine:arsenite As-methyltransferase
Comments: An enzyme of the biotransformation pathway that forms dimethylarsinate from inorganic arsenite and arsenate. It methylates arsenite to form methylarsonate, Me-AsO3H2, which is reduced by EC 1.20.4.2, methylarsonate reductase, to methylarsonite, Me-As(OH)2. Methylarsonite is also a substrate for this enzyme (EC 2.1.1.137), which converts it into the much less toxic compound dimethylarsinate (cacodylate), Me2As(O)-OH.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, UM-BBD, CAS registry number: 167140-41-2
References:
1.  Zakharyan, R.A. and Aposhian, H.V. Enzymatic reduction of arsenic compounds in mammalian systems: the rate-limiting enzyme of rabbit liver arsenic biotransformation is MMA(V) reductase. Chem. Res. Toxicol. 12 (1999) 1278–1283. [DOI] [PMID: 10604879]
2.  Zakharyan, R.A., Ayala-Fierro, F., Cullen, W.R., Carter, D.M. and Aposhian, H.V. Enzymatic methylation of arsenic compounds. VII. Monomethylarsonous acid (MMAIII) is the substrate for MMA methyltransferase of rabbit liver and human hepatocytes. Toxicol. Appl. Pharmacol. 158 (1999) 9–15. [DOI] [PMID: 10387927]
3.  Zakharyan, R.A., Wildfang, E. and Aposhian, H.V. Enzymatic methylation of arsenic compounds. III. The marmoset and tamarin, but not the rhesus, monkeys are deficient in methyltransferases that methylate inorganic arsenic. Toxicol. Appl. Pharmacol. 140 (1996) 77–84. [DOI] [PMID: 8806872]
4.  Zakharyan, R.A., Wu, Y., Bogdan, G.M. and Aposhian, H.V. Enzymatic methylation of arsenic compounds: assay, partial purification, and properties of arsenite methyltransferase and monomethylarsonic acid methyltransferase of rabbit liver. Chem. Res. Toxicol. 8 (1995) 1029–1038. [PMID: 8605285]
5.  Lin, S., Shi, Q., Nix, F.B., Styblo, M., Beck, M.A., Herbin-Davis, K.M., Hall, L.L., Simeonsson, J.B. and Thomas, D.J. A novel S-adenosyl-L-methionine:arsenic(III) methyltransferase from rat liver cytosol. J. Biol. Chem. 277 (2002) 10795–10803. [DOI] [PMID: 11790780]
[EC 2.1.1.137 created 2000, (EC 2.1.1.138 incorporated 2003), modified 2003]
 
 
EC 2.1.1.138      
Deleted entry:  methylarsonite methyltransferase. Reaction due to EC 2.1.1.137, arsonite methyltransferase
[EC 2.1.1.138 created 2000, deleted 2003]
 
 
EC 2.1.1.139     
Accepted name: 3′-demethylstaurosporine O-methyltransferase
Reaction: S-adenosyl-L-methionine + 3′-demethylstaurosporine = S-adenosyl-L-homocysteine + staurosporine
Other name(s): 3′-demethoxy-3′-hydroxystaurosporine O-methyltransferase; staurosporine synthase
Systematic name: S-adenosyl-L-methionine:3′-demethylstaurosporine O-methyltransferase
Comments: Catalyses the final step in the biosynthesis of staurosporine, an alkaloidal antibiotic that is a potent inhibitor of protein kinases, especially protein kinase C.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 212906-74-6
References:
1.  Weidner, S., Kittelmann, M., Goeke, K., Ghisalba, O. and Zahner, H. 3′-Demethoxy-3′-hydroxystaurosporine-O-methyltransferase from Streptomyces longisporoflavus catalyzing the last step in the biosynthesis of staurosporine. J. Antibiot. (Tokyo) 51 (1998) 679–682. [PMID: 9727395]
[EC 2.1.1.139 created 2000]
 
 


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