EFFECT OF ETHANOL AND FORMATE RADICALS ON ERYTHROCYTE-MEMBRANE PROTEINS

Purpose: The effect of ethanol and formate radicals on the major prote ins of human erythrocyte membranes has been investigated. Materials an d methods: Human erythrocyte ghosts and of erythrocyte ghosts stripped of peripheric proteins were irradiated in phosphate buffer with 100 m mol dm(-3) ethanol or 100 mmol dm(-3) formate under N-2 or N2O. The al terations of the proteins were investigated by SDS-polyacrylamide gel electrophoresis and high-performance gel permeation chromatography. Re sults: In contrast to previous results on ribonuclease and on serum al bumin the ethanol radicals were found to have a higher efficiency to d amage erythrocyte membrane proteins than the formate radicals. Spectri n (Bands 1 and 2) and capnophorin (Band 3) showed the highest radiatio n-induced loss of all membrane proteins. When cysteamine or dithiothre itol 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 radiosensi tivity of spectrin and capnophorin to primary radicals. Similarly to s oluble proteins, membrane-associated proteins are more significantly d amaged by ethanol radicals than by formate radicals.