Effect of dietary protein and tryptophan and the turnover of rat liver ornithine aminotransferase.

Under controlled conditions of diet, age, and animal management we confirmed our earlier studies that the fractional turnover rate constant of rat liver ornithine aminotransferase (L-ornithine:2-oxoacid aminotransferase, EC 2.6.1.13) was about 0.4 day-1 when estimated by tracer technique. However, when estimated by the kinetics of enzyme activity perturbation during dietary induction or return to normal levels, a value of about 0.7 day-1 was obtained. This discrepancy may now be attributed in part to a transistory change in the fractional rate constant during enzyme adaption.