[Kinetic mechanism of chicken liver mitochondrial malatedehydrogenase (author's transl)]

Abstract

Kinetic mechanism of chicken liver mitochondrial malatedehydrogenase is established from the initial reaction rates and reaction product inhibition. The results obtained in the reduction of NAD+ (pH 10) allow the formulation of an ordered bi-bi mechanism in which the coenzyme is the first substrate added to the enzyme. Inhibition by the reaction products and by the excess of the very substrates, reveals the formation of the E-oxaloacetate; E-L-malate; E-NAD+-oxaloacetate; E.NAD+-NADH; E-NADH-NADH and E-NAD-NAD+ abortive complexes, the significance of which may be checked under defined experimental conditions. Enzyme inhibition by ATP, ADP and AMP in the reduction of NAD+ (pH10), accords with the proposed mechanism and proceeds via formation of the E-nucleotide and E-NAD+-nucleotide inactive complexes.