Immunological studies of propionyl CoA carboxylase in livers and fibroblasts of patients with propionic acidemia.

Antiserum prepared against homogeneous pig heart propionyl CoA carboxylase cross-reacted with human propionyl CoA carboxylase, and was used to demonstrate the presence of immunological cross-reacting material in extracts from the livers of three patients and from fibroblasts of four patients with propionic acidemia representing three major propionyl CoA carboxylase-deficient genetic complementation groups, pcc A, pcc C and bio. Since the quantity of cross-reacting material in the propionyl CoA carboxylase-deficient livers and enzyme-deficient fibroblast cell lines was comparable to that in normal tissues while showing less than five percent of the normal enzyme activity, these patients must synthesize normal or near-normal quantities of an enzymatically inactive propionyl CoA carboxylase protein. In addition, no appreciable change in the amount of cross-reacting material was found in the biotin-responsive bio fibroblasts after incubation with supplemental biotin despite a sixteen-fold increase in enzyme activity suggesting that the defect in the bio mutant involves the activation rather than the synthesis of a pre-existing normal apoenzyme.