Hysteretic nature of NADH substrate inhibition of bovine liver glutamate dehydrogenase.

NADH substrate inhibition of bovine liver glutamate dehydrogenase appears to be eliminated at enzyme concentrations above 0.5mg/ml. Since the inhibition cannot be restored by preincubation of the enzyme with any substrate or product combination, the release of inhibition had previously been considered the result of enzyme polymerization. Benzene-saturated solutions, however, increase the extent of enzyme polymerization without affecting the NADH inhibition. These and related control measurements demonstrate that the release of substrate inhibition is the result of a hysteretic transition of an enzyme central and transitory complex.