Epitope mapping of a monoclonal antibody to human glutathione transferase P1–1 the binding of which is inhibited by glutathione

Abstract

Although the three-dimensional structure of human glutathione transferase (GST) P1-1 crystallized with a GSH analogue has been reported, its structure in the non-complexed form has not been determined. Four monoclonal antibodies to GST P1-1 were produced to facilitate structural analysis. Of these, one, clone d-1 of IgG #a isotype, dose-dependently inhibited the activity of GST P1-1 but did not affect the activities of either GST A1-1 or M1-1. On immunoblotting, the antibody reacted strongly with GST P1-1 and weakly with rat GST-P and mouse GST-II, indicating cross-reactivity with Pi-class forms but preferential reactivity with GST P1-1. When GST P1-1 and the antibody were incubated in the presence of 60 µM GSH, no inhibition of activity was found, whereas 1-chloro-2,4-dinitrobenzene had no effect at concentrations up to 10 µM. The binding of GST P1-1