Some properties of propionyl CoA carboxylase partially purified from human liver

Abstract Some properties of propionyl CoA carboxylase partially purified from human liver are described. The human enzyme is biotin linked, has a pH optimum between 8.0–8.5 and is activated by the monovalent cations NH 4 + , K + , Cs + and Rb + . Li + , Na + and tetramethylammonium bromide do not produce activation. The enzyme preparation catalyses the carboxylation of butyryl and acetyl CoA at a rate of 5% and 2%, respectively, of that at which propionyl CoA is carboxylated. The apparent K m of activation for K + was 4.5 × 10 −3 m , and for NH 4 + was 5.5 × 10 −3 m . The pH optimum, biotin requirement and the activation by the above monovalent cations compare with the properties described for purified bovine liver and porcine heart propionyl CoA carboxylase.