Effect of ethanol and formate radicals on erythrocyte membrane proteins

Abstract

. Purpose : The effect of ethanol and formate radicals on the major proteins of human erythrocyte membranes has been investigated. Materials and methods : Human erythrocyte ghosts and of erythrocyte ghosts stripped of peripheric proteins were irradiated in phosphate buffer with 100 mmol dm 3 ethanol or 100 mmol dm 3 formate under N or N O. The alterations of 2 2 the proteins were investigated by SDS-polyacrylamide gel electrophoresis and high-performance gel permeation chromatography. Results : In contrast to previous results on ribonuclease and on serum albumin the ethanol radicals were found to have a higher efficiency to damage erythrocyte membrane proteins than the formate radicals. Spectrin (Bands 1 and 2) and capnophorin (Band 3) showed the highest radiation-induced loss of all membrane proteins. When cysteamine or dithiothreitol were added to the erythrocyte ghosts with a similar OH-scavenging capacity as ethanol or formate, no degradation or aggregation of the membrane proteins could be observed even after a dose as high as 1800 Gy. Conclusions : The results of this study confirm the high radiosensitivity of spectrin and capnophorin to primary radicals. Similarly to soluble proteins, membrane-associated proteins are more significantly damaged by ethanol radicals than by formate radicals.