Investigations on Pantothenic Acid and Its Related Compounds

XX. Biochemical Studies. (ll). Enzymatic Conversion of 2'-Ketopantothenate to D-Pantothenate in Rat

Abstract

The in vivo and in vitro conversion of 2'-ketopantothenate to a-pantothenate was demonstrated in rat. The enzyme which catalyzed the reductive conversion was localized in the microsomal and the soluble fractions of rat liver, and both enzymes required NADH or NADPH as a cofactor. Two distinct enzyme systems were found in the microsomal fraction. One was NADH-dependent and the other NADPH-depen-dent. The NADPH-dependent activity was stimulated in an anaerobic condition and increased by phenobarbital treatment of rat. The soluble enzyme was different from the microsomal enzymes in pH optimum, the effect of the substrate concentration and thermostability.