IUBMB Enzyme Nomenclature


Accepted name: O-acetylhomoserine aminocarboxypropyltransferase

Reaction: O-acetyl-L-homoserine + methanethiol = L-methionine + acetate

For diagram click here.

Other name(s): O-acetyl-L-homoserine acetate-lyase (adding methanethiol); O-acetyl-L-homoserine sulfhydrolase; O-acetylhomoserine (thiol)-lyase; O-acetylhomoserine sulfhydrolase; methionine synthase (misleading)

Systematic name: O-acetyl-L-homoserine:methanethiol 3-amino-3-carboxypropyltransferase

Comments: Also reacts with other thiols and H2S, producing homocysteine or thioethers. The name methionine synthase is more commonly applied to EC, methionine synthase. The enzyme from baker's yeast also catalyses the reaction of EC cysteine synthase, but more slowly.

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number: 37290-90-7


1. Kerr, D. O-Acetylhomoserine sulfhydrylase (Neurospora). Methods Enzymol. 17B (1971) 446-450.

2. Smith, I.K. and Thompson, J.F. Utilization of S-methylcysteine and methylmercaptan by methionineless mutants of Neurospora and the pathway of their conversion to methionine. II. Enzyme studies. Biochim. Biophys. Acta 184 (1969) 130-138. [PMID: 5791104]

3. Yamagata, S. and Takeshima, K. O-Acetylserine and O-acetylhomoserine sulfhydrylase of yeast. Further purification and characterization as a pyridoxal enzyme. J. Biochem. (Tokyo) 80 (1976) 777-785. [PMID: 795806]

4. Yamagata, S. O-Acetylserine and O-acetylhomoserine sulfhydrylase of yeast. Subunit structure. J. Biochem. (Tokyo) 80 (1976) 787-797. [PMID: 795807]

5. Yamagata, S., Takeshima, K. and Naikai, N. Evidence for the identity of O-acetylserine sulfhydrylase with O-acetylhomoserine sulfhydrylase in yeast. J. Biochem. (Tokyo) 75 (1974) 1221-1229. [PMID: 4609980]

6. Yamagata, S. Roles of O-acetyl-L-homoserine sulfhydrylases in micro-organisms. Biochimie 71 (1989) 1125-1143. [PMID: 2517474]

7. Shimizu, H., Yamagata, S., Masui, R., Inoue, Y., Shibata, T., Yokoyama, S., Kuramitsu, S. and Iwama, T. Cloning and overexpression of the oah1 gene encoding O-acetyl-L-homoserine sulfhydrylase of Thermus thermophilus HB8 and characterization of the gene product. Biochim. Biophys. Acta 1549 (2001) 61-72. [PMID: 11566369]

[EC created 1972 as EC, transferred 2002 to EC]

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