Kinetic studies on the flavoprotein component (E 3) of rat brain pyruvate dehydrogenase multienzyme complex

Abstract

1. 1. Kinetic studies were made with the effects of pyruvate and coenzyme A (CoA) on the reactions catalyzed by dihydrolipoate dehydrogenase (E 3, a flavoprotein). 2. 2. Pyruvate does not have an appreciable effect on the reactions catalyzed by E 3. However, CoA noncompetitively inhibits E 3 with both lipoamide and NADH as the variable substrates. 3. 3. These results suggest the possible interaction between the component-enzymes of PDHC through their physical association and thus offer a possible explanation for the anomalous product inhibition experiments which were observed previously by us (Ngo & Barbeau, 1978).