Effects of chemical modification of membrane thiol groups on hemolysis of human erythrocytes under hydrostatic pressure

Abstract

Membrane stability of the human erythrocyte under high pressure was examined by modifying membrane SH-groups with NEM or diamide. Hemolysis at 200 MPa of chemically modified erythrocytes was significantly suppressed by the prolonged incubation of them in a reagent-free medium above 30°C prior to the application of high pressure. However, there was no detectable change regarding membrane phospholipid distribution, CD spectra and SDS-PAGE of membrane proteins, and intracellular K + concentration during the incubation. On the other hand, the data of protein-spin labeling and SH-group content showed that the SH-groups buried in membrane proteins appeared on their surface by conformational changes of membrane proteins induced during the incubation. The extraction of peripheral proteins from NEM-treated membranes in 0.1 N NaOH was considerably suppressed by the incubation. These results suggest that, upon chemical modification of membrane SH-groups, protein-protein interactions are modulated during prolonged incubation above 30°C so that high pressure-induced hemolysis is suppressed.