Propionyl-CoA carboxylase
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Propionyl-CoA carboxylase (EC 6.4.1.3, PCC) catalyses the carboxylation reaction of propionyl-CoA in the mitochondrial matrix. PCC has been classified both as a ligase[1] and a lyase.[2] The enzyme is biotin-dependent. The product of the reaction is (S)-methylmalonyl CoA.
- ATP + propionyl-CoA + HCO3− <=> ADP + phosphate + (S)-methylmalonyl-CoA
Propionyl-CoA carboxylase | |||||||||
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Identifiers | |||||||||
EC no. | 6.4.1.3 | ||||||||
CAS no. | 9023-94-3 | ||||||||
Databases | |||||||||
IntEnz | IntEnz view | ||||||||
BRENDA | BRENDA entry | ||||||||
ExPASy | NiceZyme view | ||||||||
KEGG | KEGG entry | ||||||||
MetaCyc | metabolic pathway | ||||||||
PRIAM | profile | ||||||||
PDB structures | RCSB PDB PDBe PDBsum | ||||||||
Gene Ontology | AmiGO / QuickGO | ||||||||
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(S)-Methylmalonyl-CoA cannot be directly utilized by animals. It is acted upon by a racemase, yielding (R)-methylmalonyl-CoA, which is then converted into succinyl-CoA by methylmalonyl-CoA mutase (one of the few metabolic enzymes which requires vitamin B12 as a cofactor). Succinyl-CoA, a Krebs cycle intermediate, is further metabolized into fumarate, then malate, and then oxaloacetate. Oxaloacetate may be transported into the cytosol to form phosphoenol pyruvate and other gluconeogenic intermediates. Propionyl-CoA is therefore an important precursor to glucose.
Propionyl-CoA is the end product of odd-chain fatty acid metabolism, including most methylated fatty acids. The amino acids valine, isoleucine, and methionine are also substrates for propionyl-CoA metabolism.