Influence of temperature on the determination of enzyme activities in human serum. gamma-Glutamyl transferase.

Optimum reaction conditions for determination of gamma-glutamyl transferase were studied at 25, 30 and 37 degrees C using a kinetic test and gamma-glutamyl-3-carboxy-4-nitranilide as substrate. There was no dependence on temperature of half saturation constants of gamma-glutamyl-3-carboxy-4-nitranilide. The corresponding constants for glycylglycine were influenced by temperature and the pH. The optimum showed a dependence upon temperature. In Arrhenius' plot, a deviation from straight line can be observed only above 35 degrees C. The influence of temperature on the determination of enzyme activities in human serum are discussed.