The Enzyme Database

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Accepted name: glycine cleavage system
Reaction: glycine + tetrahydrofolate + NAD+ = 5,10-methylenetetrahydrofolate + NH3 + CO2 + NADH
Other name(s): GCV
Systematic name: glycine:NAD+ 2-oxidoreductase (tetrahydrofolate-methylene-adding)
Comments: The glycine cleavage (GCV) system is a large multienzyme complex that belongs to the 2-oxoacid dehydrogenase complex family, which also includes EC, branched-chain α-keto acid dehydrogenase system, EC, 2-oxoglutarate dehydrogenase system, EC, pyruvate dehydrogenase system, and EC, acetoin dehydrogenase system. The GCV system catalyses the reversible oxidation of glycine, yielding carbon dioxide, ammonia, 5,10-methylenetetrahydrofolate and a reduced pyridine nucleotide. Tetrahydrofolate serves as a recipient for one-carbon units generated during glycine cleavage to form the methylene group. The GCV system consists of four protein components, the P protein (EC, glycine dehydrogenase (aminomethyl-transferring)), T protein (EC, aminomethyltransferase), L protein (EC, dihydrolipoyl dehydrogenase), and the non-enzyme H protein (lipoyl-carrier protein). The P protein catalyses the pyridoxal phosphate-dependent liberation of CO2 from glycine, leaving a methylamine moiety. The methylamine moiety is transferred to the lipoic acid group of the H protein, which is bound to the P protein prior to decarboxylation of glycine. The T protein catalyses the release of ammonia from the methylamine group and transfers the remaining C1 unit to tetrahydrofolate, forming 5,10-methylenetetrahydrofolate. The L protein then oxidizes the lipoic acid component of the H protein and transfers the electrons to NAD+, forming NADH.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
1.  Motokawa, Y. and Kikuchi, G. Glycine metabolism by rat liver mitochondria. Reconstruction of the reversible glycine cleavage system with partially purified protein components. Arch. Biochem. Biophys. 164 (1974) 624–633. [DOI] [PMID: 4460882]
2.  Hiraga, K. and Kikuchi, G. The mitochondrial glycine cleavage system. Functional association of glycine decarboxylase and aminomethyl carrier protein. J. Biol. Chem. 255 (1980) 11671–11676. [PMID: 7440563]
3.  Okamura-Ikeda, K., Fujiwara, K. and Motokawa, Y. Purification and characterization of chicken liver T-protein, a component of the glycine cleavage system. J. Biol. Chem. 257 (1982) 135–139. [PMID: 7053363]
4.  Fujiwara, K., Okamura-Ikeda, K. and Motokawa, Y. Mechanism of the glycine cleavage reaction. Further characterization of the intermediate attached to H-protein and of the reaction catalyzed by T-protein. J. Biol. Chem. 259 (1984) 10664–10668. [PMID: 6469978]
5.  Okamura-Ikeda, K., Ohmura, Y., Fujiwara, K. and Motokawa, Y. Cloning and nucleotide sequence of the gcv operon encoding the Escherichia coli glycine-cleavage system. Eur. J. Biochem. 216 (1993) 539–548. [DOI] [PMID: 8375392]
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