DENATURATION AND INACTIVATION OF ENZYME PROTEINS: XI. INACTIVATION AND DENATURATION OF GLUTAMIC ACID DEHYDROGENASE BY UREA, AND THE EFFECT OF ITS COENZYME ON THESE PROCESSES

Abstract

Thrice recrystallized GAD undergoes a reversible, competitive inhibition by urea at a relatively low concentration (2 [image]). (Irreversible) denaturation and inactivation of GAD by urea (> 3.6 [image]) are protected by DPN (diphosphopyridine nucleotide) or glutamate7 and rather accelerated by DPNH (reduced DPN). Digestibility of GAD by bacterial proteinase of B. subtilis is influenced in similar ways by substrate and coenzymes. A configurational change upon combining with DPN or DPNH is suggested.