The effect of pH on the characteristics of the binding of nicotinamide–adenine dinucleotide by nicotinamide–adenine dinucleotide specific isocitrate dehydrogenase from pea mitochondria

Abstract

1. The effect of pH on the Vmax. and concentration of NAD+ at half-maximum velocity at a constant isocitrate concentration was examined, and the results were related to the requirements for binding of H+ ions to the enzyme. 2. The effect of varying the NAD+ concentration on the pH optimum with constant isocitrate concentration was studied. 3. A comparison has been made between the effect of isocitrate concentration on the characteristics of binding of NAD+ and the effect of NAD+ concentration on the characteristics of isocitrate binding at three different pH values. 4. The mechanistic and metabolic significance of these studies is considered.