ROSE BENGAL BINDING AFFINITY OF THE HUMAN HEPATIC GLUTATHIONE S-TRANSFERASES

Abstract

In order to know the function as ligandin of the human hepatic glutathione S-transferases (GST), rose bengal (RB) binding affinities of purified hepatic isozymes of GST and hepatic cytosolic proteins including GST obtained from various liver diseases were investigated using fluorospectrophotometric method.
Purified isozymes such as cationic (C1 and C2), neutral (N1) and anionic (A1) showed not much differences in the affinity (Kd: 0.020-0.068μM) for RB binding. Moreover, binding stoichiometry revealed a single RB binding site on one molecule of all species of GST isozyme.
From the evaluation of 17 samples of hepatic cytosol, the GST activity, assayed with 1-chloro-2, 4-dinitrobenzene as substrate, the GST content measured by SDS-polyacrylamide gel electrophoresis and subsequent densitometry, and the number of RB binding site calculated from the binding kinetics showed significantly positive correlations each other. The result suggested that the GST enzyme function might be consistent with the function as ligandin at least in the human liver.