The reaction is observed only in the direction of sarcosine 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 sarcosine binding and methylamine 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 126.96.36.199 (glycine reductase) and EC 188.8.131.52 (betaine reductase).
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]
Hormann, K. and Andreesen, J.R. Reductive cleavage of sarcosine and betaine by Eubacterium acidaminophilum via enzyme systems different from glycine reductase. Arch. Microbiol.153 (1989) 50–59.