Szewczuk A, Wellman-Bednawska M
Clin Chim Acta. 1978 Mar 1;84(1-2):19-26. doi: 10.1016/0009-8981(78)90471-0.
By the phthaloyl method less toxic and readily soluble gamma-L-glutamyl-p-aminobenzoic acid was synthesized. This substance was used as a substrate for gamma-glutamyltranspeptidase activity assay in blood serum and urine. Close correlation was shown between the results obtained with the new method and with the old one which used gamma-L-glutamyl-p-nitroanilide.