Failure of N-Ethyl Maleimide to React With Sulfhydryl Groups of Intact Human Erythrocytes

Abstract

Certain sulfhydryl reagents such as p-chloromercuribenzoic acid hemolyze human erythrocytes in a predictable manner. N-ethyl maleimide does not hemolyze human erythrocytes although it reacts freely with the –SH groups of cysteine, glutathione and ergothionine. Also N-ethyl maleimide reacts avidly with the –SH groups of human erythrocytes previously hemolyzed by freezing. These findings indicate the envelope of the intact erythrocyte prevents access of N-ethyl maleimide to the critical –SH groups of the intact erythrocyte or that freezing exposes the crucial –SH groups by altering the natural configuration of the proteins. Submitted on April 6, 1956