MONOAMINE-OXIDASE ACTIVITY IN RAT-LIVER UNDER VITAMIN-B-12 DEFICIENCY

Monoamine oxidase (MAO-B) activity in liver homogenates and mitochondr ia from control and B-12-deficients rats was studied under various fun ctional states of the mitochondria. Preincubation of preparations at 3 2 degrees C increased MAO affinity for benzylamine for control but not for vitamin B-12-deficient rats. Addition of succinate to the incubat ion medium was accompanied by a decrease in K-m and an increase in V-m ax in both groups of animals. Under vitamin B-12 deficiency a correlat ion between decreased MAO-B activity, decreased succinate oxidation ra te, and decreased transmembrane potential was found.