Effect of X-irradiation on erythrocyte membrane proteins. Primary radicals

The effect of X-irradiation on the major proteins of human erythrocyte membranes have been examined. Samples of human erythrocyte ghosts and stripped ghosts were irradiated (up to 1.5 kGy) under air, N2 or N2O. The effects on the main erythrocyte membrane proteins as well as on aggregate formation were investigated using sodium dodecyl sulphate-polyacrylamide gel electrophoresis and high-performance gel permeation chromatography. Experiments were carried out with or without dithiothreitol as a reducing agent. The main peripheral protein of the erythrocyte membrane, spectrin, is more radio-sensitive than the other membrane proteins. Degradation was mainly due to aggregation and was increased by excluding oxygen. Since radiolysis under N2O instead of N2 enhanced the loss of spectrin, OH radicals seemed to be especially effective. Under anaerobic conditions the degradation of band 3 material could also be observed. In stripped erythrocyte ghosts the radiosensitivity of this integral protein was similar to that of spectrin.