The diversity of sulfhydryl groups in the human erythrocyte membrane

Human bank blood erythrocytes were exposed to the mercurials p‐chloromercuribenzoate (PCMB), chlormerodrin (CM), p‐chloromercuribenzenesulfonate (PCMBS), and 1‐bromomercuri‐2‐hydroxypropane (BMHP) for different time intervals, at different concentrations and in combination with n‐ethylmaleimide (NEM) added before, and 2‐mercaptoethylguanidine (MEG) and reduced glutathione (GSH) added after the mercurial. Binding patterns of the mercurials to the cells and effects on permeability of the cells were measured. The results indicate that the erythrocyte membrane contains multiple classes of sulfhydryl groups, alteration of which has a variety of effects on cell permeability. PCMB, chlormerodrin and PCMBS react with at least three classes of sulfhydryls, two of which are associated with the sodium‐potassium barrier and, when altered, result in potassium loss, sodium accumulation and hemolysis. BMHP reacts with at least two classes of sulfhydryls, one of which is associated with permeability, and, when altered, results in hemolysis in isotonic solutions of choline chloride or lactose. The results provide additional insight into the structure and function of the erythrocyte membrane.