Effect of ethanol and formate radicals on erythrocyte membrane proteins.

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 N2 or N2O. The alterations of 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.