HISTOCHEMICAL AND ULTRASTRUCTURAL DEMONSTRATION OF γ-GLUTAMYL TRANSPEPTIDASE ACTIVITY

Abstract

A simultaneous coupling azo dye method for the histochemical demonstration of γ-glutamyl transpeptidase activity using the new substrate γ-glutamyl-4-methoxy-2-naphthylamide has been described. The method appears superior to previously reported methods for γ-glutamyl transpeptidase activity and can easily be modified for the electron microscopic localization of the enzyme by bridging osmium to the copper chelate of the azo dye via thiocarbohydrazide. The optimum conditions for the histochemical reaction were developed and the distribution of enzymatic activity in the tissues of the rat is described for light microscopy and with rat pancreas for electron microscopy. The electron-opaque deposits were seen in the endoplasmic reticulum in the vicinity of the zymogen granules in the apical portion of the acinar cell.