Abstract
Assaying conditions of γ-Glutamyltransferase (γ-GTP EC.2.3.2.2) activity in serum were studied by using L-γ-glutamy1-3-hydroxymethy1-4-nitroanilide as substrate. This new substrate is readily soluble even in a neutral aqueous solution, and the substrate solution is stable at least for five months at 5°C. The measurment of γ-GTP activity was carried out under the conditions of pH 8.2, 67mmol/l glycylglycine and 1.5mmol/l substrate. γ-GTP activity in human serum was determined as almost identical value with that obtained under the conditions recomended by Scandinavian Society of Clinical Chemistry (S. S. C. C.) using L-γ-glutamyl-4-nitroanilide. Further, the values of γ-GTP activities obtained from pig or bovine kidney by proposed method also closely approximated to that measured by S. S. C. C. method. The results of determination by using Hitachi automatic analizer model 7050 were as follows; the dynamic range was 0-2,000U/l, the reproducibility of a sample (X=66U/l) presenied S. D. =0.63, C. V. =0.95% and a good correlation with two recomended methods that are S. S. C. C. and l. F. C. C. was demonstrated for serum γ-GTP activity (r=0.999).
