Catalytic and structural properties of brain glutamate decarboxylase

Abstract

An homogeneous glutamate decarboxylase isolated from porcine brain contains 0.8 ㏖ of a tightly bound pyridoxal-5-phosphate per one mole enzyme dimer. Upon addition of exogeneous pyridoxal-5-P, the enzyme acquires maximum catalytic activity. The purified enzyme was deactivated by sulfhydryl reagents and mycotoxin patulin. Recovery from inhibition after the addition of dithiothreitol or 2-mercaptoetnanol suggests that critical sulfhydryl residues in the catalytic domain of the enzyme are connected with catalytic activity, and that the mycotoxin patulin reacts with these sulfhydryl residues of the enzyme.