Kinetic analysis of rat liver sorbitol dehydrogenase.

1. A steady state kinetic investigation was performed on an improved preparation of rat-liver sorbitol dehydrogenase (L-iditol: NAD-oxidoreductase, EC 1.1.1.14). 2. Data analyses indicate the enzyme follows a rapid equilibrium random mechanism in the direction of sorbitol oxidation and a random mechanism in the direction of fructose reduction. 3. Kinetic constants were: K m NAD 0.082 mM; K m sorbitol 0.38 mM; K m NADH 67 microns; K m fructose 136 mM. 4. Evidence is adduced to indicate the more rapid reverse (fructose reduction) reaction is susceptible to metabolic control by formation of abortive enzyme fructose-NAD and enzyme-NADH-sorbitol complexes.