Glycine decarboxylase also known as glycine cleavage system P protein or glycine dehydrogenase is an enzyme that in humans is encoded by the GLDCgene.[1][2][3]
glycine + H-protein-lipoyllysine <math>\rightleftharpoons</math> H-protein-S-aminomethyldihydrolipoyllysine + CO2
Thus, the two substrates of this enzyme are glycine and H-protein-lipoyllysine, whereas its two products are H-protein-S-aminomethyldihydrolipoyllysine and CO2.
This enzyme belongs to the family of oxidoreductases, specifically those acting on the CH-NH2 group of donors with a disulfide as acceptor. This enzyme participates in glycine, serine and threonine metabolism. It employs one cofactor, pyridoxal phosphate.
Function
Glycine decarboxylase is the P-protein of the glycine cleavage system in eukaryotes. The glycine cleavage system catalyzes the degradation of glycine. The P protein binds the alpha-amino group of glycine through its pyridoxal phosphate cofactor. Carbon dioxide is released and the remaining methylamine moiety is then transferred to the lipoamide cofactor of the H protein.
Degradation of glycine is brought about by the glycine cleavage system, which is composed of four mitochondrial protein components: P protein (a pyridoxal phosphate-dependent glycine decarboxylase), H protein (a lipoic acid-containing protein), T protein (a tetrahydrofolate-requiring enzyme), and L protein (a lipoamide dehydrogenase).[3]
↑Kume A, Koyata H, Sakakibara T, Ishiguro Y, Kure S, Hiraga K (Mar 1991). "The glycine cleavage system. Molecular cloning of the chicken and human glycine decarboxylase cDNAs and some characteristics involved in the deduced protein structures". J Biol Chem. 266 (5): 3323–9. PMID1993704.
↑Kure S, Narisawa K, Tada K (Mar 1991). "Structural and expression analyses of normal and mutant mRNA encoding glycine decarboxylase: three-base deletion in mRNA causes nonketotic hyperglycinemia". Biochem Biophys Res Commun. 174 (3): 1176–82. doi:10.1016/0006-291X(91)91545-N. PMID1996985.
Hiraga K, Kikuchi G (1980). "The mitochondrial glycine cleavage system. Functional association of glycine decarboxylase and aminomethyl carrier protein". J. Biol. Chem. 255 (24): 11671&ndash, 6. PMID7440563.
Perham RN (2000). "Swinging arms and swinging domains in multifunctional enzymes: catalytic machines for multistep reactions". Annu. Rev. Biochem. 69: 961&ndash, 1004. doi:10.1146/annurev.biochem.69.1.961. PMID10966480.
Broadwater JA, Haas JA, Fox BG, Booker SJ (2005). "Expression, purification, and physical characterization of Escherichia coli lipoyl(octanoyl)transferase". Protein. Expr. Purif. 39 (2): 269&ndash, 82. doi:10.1016/j.pep.2004.10.021. PMID15642479.*Applegarth DA, Toone JR (2001). "Nonketotic hyperglycinemia (glycine encephalopathy): laboratory diagnosis". Mol. Genet. Metab. 74 (1–2): 139–46. doi:10.1006/mgme.2001.3224. PMID11592811.
Sakakibara T, Koyata H, Ishiguro Y, et al. (1991). "One of the two genomic copies of the glycine decarboxylase cDNA has been deleted at a 5' region in a patient with nonketotic hyperglycinemia". Biochem. Biophys. Res. Commun. 173 (3): 801–6. doi:10.1016/S0006-291X(05)80858-7. PMID2268343.
Burton BK, Pettenati MJ, Block SM, et al. (1989). "Nonketotic hyperglycinemia in a patient with the 9p- syndrome". Am. J. Med. Genet. 32 (4): 504–5. doi:10.1002/ajmg.1320320416. PMID2773994.
Hayasaka K, Kochi H, Hiraga K, Kikuchi G (1981). "Purification and properties of glycine decarboxylase, a component of the glycine cleavage system, from rat liver mitochondria and immunochemical comparison of this enzyme from various sources". J. Biochem. 88 (4): 1193–9. PMID6778858.
Takayanagi M, Kure S, Sakata Y, et al. (2000). "Human glycine decarboxylase gene (GLDC) and its highly conserved processed pseudogene (psiGLDC): their structure and expression, and the identification of a large deletion in a family with nonketotic hyperglycinemia". Hum. Genet. 106 (3): 298–305. doi:10.1007/s004390051041. PMID10798358.
Toone JR, Applegarth DA, Coulter-Mackie MB, James ER (2000). "Biochemical and molecular investigations of patients with nonketotic hyperglycinemia". Mol. Genet. Metab. 70 (2): 116–21. doi:10.1006/mgme.2000.3000. PMID10873393.
Toone JR, Applegarth DA, Coulter-Mackie MB, James ER (2001). "Recurrent mutations in P- and T-proteins of the glycine cleavage complex and a novel T-protein mutation (N145I): a strategy for the molecular investigation of patients with nonketotic hyperglycinemia (NKH)". Mol. Genet. Metab. 72 (4): 322–5. doi:10.1006/mgme.2001.3158. PMID11286506.
Kure S, Kojima K, Ichinohe A, et al. (2002). "Heterozygous GLDC and GCSH gene mutations in transient neonatal hyperglycinemia". Ann. Neurol. 52 (5): 643–6. doi:10.1002/ana.10367. PMID12402263.
Dinopoulos A, Kure S, Chuck G, et al. (2006). "Glycine decarboxylase mutations: a distinctive phenotype of nonketotic hyperglycinemia in adults". Neurology. 64 (7): 1255–7. doi:10.1212/01.WNL.0000156800.23776.40. PMID15824356.
Flusser H, Korman SH, Sato K, et al. (2006). "Mild glycine encephalopathy (NKH) in a large kindred due to a silent exonic GLDC splice mutation". Neurology. 64 (8): 1426–30. doi:10.1212/01.WNL.0000158475.12907.D6. PMID15851735.
Boneh A, Korman SH, Sato K, et al. (2005). "A single nucleotide substitution that abolishes the initiator methionine codon of the GLDC gene is prevalent among patients with glycine encephalopathy in Jerusalem". J. Hum. Genet. 50 (5): 230–4. doi:10.1007/s10038-005-0243-y. PMID15864413.
Korman SH, Wexler ID, Gutman A, et al. (2006). "Treatment from birth of nonketotic hyperglycinemia due to a novel GLDC mutation". Ann. Neurol. 59 (2): 411–5. doi:10.1002/ana.20759. PMID16404748.