Behaviour of L-gamma-glutamyl-4-nitroanilide and L-gamma-glutamyl-3-carboxy-4-nitroanilide with respect to gamma-glutamyltransferases of different origin.

In this paper we compare the measurement of catalytic activity concentrations of gamma-glutamyltransferase with the non-carboxylated and the carboxylated substrate in preparations of different origin. Fresh human sera, commercial test sera and preparations of gamma-glutamyltransferase purified from human liver, porcine kidney and bovine kidney were used as sample materials. When assayed with both substrates preparations of gamma-glutamyltransferase from bovine kidney behaved in a different manner as did the enzyme in preparations from human liver or porcine kidney and the enzyme in fresh human sera. On account of the results obtained with both substrates we classified the commercial test sera for their enrichment using multi-inductive component analysis. The differences observed for the various methods of determination seem to have significance in quality control.