Which of the following conversions does not require Biotin as a cofactor?
(A) Gamma carboxylation of glutamate (B) Acetyl Co-A to Malonyl Co-A (C) Propionyl Co-A to methyl malonyl Co-A (D) Pyruvate to oxaloacetate
(A) Ans: A. Gamma carboxylation of glutamate(Ref: Harrison 19/e p96e-5; Harper 30/e p550, 561)Gamma carboxylation of glutamate:Carried out by Gamma-glutamyl carboxylase.Gamma-glutamyl carboxylase:Vitamin-K dependent enzyme.Catalyzes post-translational modification of vitamin K-dependent proteins.Biotin:Transfers carbon dioxide in reactions like acetyl-CoA carboxylase, pyruvate carboxylase, propionyl-CoA carboxylase & methylcrotonyl-CoA carboxylase.Biotin functions to transfer carbon dioxide in reactionsPyruvate carboxylasePyruvate (3C) to oxaloacetate (4C) in gluconeogenesisdegAcetyl-CoA carboxylaseAcetyl-CoA (2C) to malonyl-CoA (3C) in lipid synthesis.Propionyl-CoA carboxylasePropionyl-Co A (3C) to methylmalonyl-CoA (4C) inMethylmalonyl CoA carboxyl Propionic acid synthesis in bacteriaMethylcrotonyl-CoA carboxylaseLeucine catabolism