Investigations on the kinetic mechanism of octopine dehydrogenase. 1. Steady-state kinetics.

The kinetic mechanism of action of octopine dehydrogenase was investigated. This enzyme catalyses the reversible dehydrogenation of D-octopine to L-arginine and pyruvate, in the presence of nicotinamide-adenine dinucleotide. Initial velocity and product inhibition studies were carried out in both directions. Most of the results are consistent with a bi-ter sequential mechanism where NAD+ binds first to the enzyme followed by D-octopine, and the products are released in the order L-arginine, pyruvate and NADH. Various kinetic parameters were determined for each reactant at 33 degrees C, at pH 9.6 for NAD reduction, at pH 6.6 for NADH oxidation.