KINETICS OF NADH OXIDATION BY PIGEON-HEART MITOCHONDRIA

Abstract

The oxidation of 1-10 μM NADH by pigeon-heart mitochondria prepared by the method of Chance and Hagihara was studied. In a medium consisting of 0.07 M sucrose, 0.23 M mannitol, 0.02 M Tris–HCl, 0.02 mM EDTA, all at pH 7.2, the concentration of NADH required for half maximal velocity was found to be approximately 5 μM. ATP and ADP appear to be competitive inhibitors of NADH oxidation. Application of Michaelis–Menten kinetics to the data yielded a Kiof 0.7 mM for both ATP and ADP. Some possible sites of inhibition by adenine nucleotides are discussed.