In enzymology, a glycine reductase (EC 1.21.4.2) is an enzyme that catalyzes the chemical reaction

acetyl phosphate + NH₃ + thioredoxin disulfide + H₂O ${\displaystyle \rightleftharpoons }$ glycine + phosphate + thioredoxin

The 4 substrates of this enzyme are acetyl phosphate, NH₃, thioredoxin disulfide, and H₂O, whereas its 3 products are glycine, phosphate, and thioredoxin.

This enzyme belongs to the family of oxidoreductases, to be specific, those acting on X-H and Y-H to form an X-Y bond with a disulfide as acceptor. The systematic name of this enzyme class is acetyl-phosphate ammonia:thioredoxin disulfide oxidoreductase (glycine-forming).

• Andreesen JR; Sonntag, D; Grimm, R; Pich, A; Eckerskorn, C; Söhling, B; Andreesen, JR (1999). "Substrate-specific selenoprotein B of glycine reductase from Eubacterium acidaminophilum. Biochemical and molecular analysis". Eur. J. Biochem. 260 (1): 38–49. doi:10.1046/j.1432-1327.1999.00107.x. PMID 10091582.
• Bednarski B, Andreesen JR, Pich A (2001). "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 (12): 3538–44. doi:10.1046/j.1432-1327.2001.02257.x. PMID 11422384.