The biosynthesis of methylcitrate.
Citrate synthase catalyses the formation in vitro of two diastereoisomers of methylcitrate from propionyl-CoA and oxaloacetate. The proportion of diastereoisomers produced is temperature-sensitive. In the presence of oxaloacetate and a thiol trap, the enzyme catalyses the exchange of both alpha-protons of propionyl-CoA with 2H2O. The pro-S-proton at the alpha-carbon atom is exchanged 15 times faster with 2H2O than is the pro-R-proton. The exchanges are over 1000 and 100 times faster respectively than Vmax. These results are interpreted in the light of recent reports that 2R,3S- and 2S,3S-methylcitrates are produced by the enzyme-catalysed condensation and also excreted by patients with propionic acidaemia.
D000214:Acyl Coenzyme A / Q000378:metabolism; D000592:Amino Acid Metabolism, Inborn Errors / Q000652:urine; D002950:Citrate (si)-Synthase / Q000378:metabolism; D002951:Citrates / Q000096:biosynthesis* / Q000652:urine; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D011422:Propionates / Q000097:blood; D011522:Protons; D013237:Stereoisomerism
D000214:Acyl Coenzyme A; D002951:Citrates; D011422:Propionates; D011522:Protons; D002950:Citrate (si)-Synthase