Reaction: acetyl phosphate + trimethylamine + thioredoxin disulfide + H2O = betaine + phosphate + thioredoxin
For diagram of reaction click here.
Glossary: betaine = glycine betaine = N,N,N-trimethylglycine
Other name(s): acetyl-phosphate trimethylamine:thioredoxin disulfide oxidoreductase (N,N,N-trimethylglycine-forming)
Systematic name: acetyl-phosphate trimethylamine:thioredoxin disulfide oxidoreductase (betaine-forming)
Comments: The reaction is observed only in the direction of betaine reduction. The enzyme from Eubacterium acidaminophilum consists of subunits A, B and C. Subunit B contains selenocysteine and a pyruvoyl group, and is responsible for betaine binding and trimethylamine release. Subunit A, which also contains selenocysteine, is reduced by thioredoxin, and is needed to convert the carboxymethyl group into a ketene equivalent, in turn used by subunit C to produce acetyl phosphate. Only subunit B distinguishes this enzyme from EC 1.21.4.2 (glycine reductase) and EC 1.21.4.3 (sarcosine reductase).
Links to other databases: BRENDA, EXPASY, KEGG, Metacyc, CAS registry number: 125752-87-6
References:
1. Wagner, M., Sonntag, D., Grimm, R., Pich, A. Eckerskorn, C., Söhling, B. and Andreesen, J.R. Substrate-specific selenoprotein B of glycine reductase from Eubacterium acidaminophilum. Eur. J. Biochem. 260 (1999) 38-49. [PMID: 10091582]
2. Bednarski, B., Andreesen, J.R. and Pich, A. In vitro processing of the proproteins GrdE of protein B of glycine reductase and PrdA of D-proline reductase from Clostridium sticklandii: formation of a pyruvoyl group from a cysteine residue. Eur. J. Biochem. 268 (2001) 3538-3544. [PMID: 11422384]