IUBMB Enzyme Nomenclature


Accepted name: L-methionine (S)-S-oxide reductase

Reaction: L-methionine + thioredoxin disulfide + H2O = L-methionine (S)-S-oxide + thioredoxin

For diagram click here and mechanism click here.

Other name(s): fSMsr; methyl sulfoxide reductase I and II; acetylmethionine sulfoxide reductase; methionine sulfoxide reductase; L-methionine:oxidized-thioredoxin S-oxidoreductase; methionine-S-oxide reductase; free-methionine (S)-S-oxide reductase

Systematic name: L-methionine:thioredoxin-disulfide S-oxidoreductase

Comments: Requires NADPH [2]. The reaction occurs in the opposite direction to that given above. Dithiothreitol can replace reduced thioredoxin. L-Methionine (R)-S-oxide is not a substrate [see EC, L-methionine (R)-S-oxide reductase].

Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, PDB, CAS registry number:


1. Black, S., Harte, E.M., Hudson, B. and Wartofsky, L. A specific enzymatic reduction of L-(–)methionine sulfoxide and a related nonspecific reduction of diulfides. J. Biol. Chem. 235 (1960) 2910-2916.

2. Ejiri, S.-I., Weissbach, H. and Brot, N. Reduction of methionine sulfoxide to methionine by Escherichia coli. J. Bacteriol. 139 (1979) 161-164. [PMID: 37234]

3. Ejiri, S.-I., Weissbach, H. and Brot, N. The purification of methionine sulfoxide reductase from Escherichia coli. Anal. Biochem. 102 (1980) 393-398. [PMID: 6999943]

4. Weissbach, H., Resnick, L. and Brot, N. Methionine sulfoxide reductases: history and cellular role in protecting against oxidative damage. Biochim. Biophys. Acta 1703 (2005) 203-212. [PMID: 15680228]

[EC created 1984 as EC, part transferred 2006 to EC]

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