STUDIES ON THE PROPERTY OF SULFHYDRYL BINDING SITE ON THE LUNG NORMAL AND CANCER CELL MEMBRANE OF CHINESE HAMSTER WITH MALEIMIDE SPIN LABELS

In this paper, five maleimide spin labels with different chain lengths were used to studythe properties of binding sites of sulfhydryl groups on the meanbrane proteins of normal cellV_79 and cancer cells V_79-B_1 in the lung of Chinese hamster. The ratio of the strongly immobi-lized component to the weakly immobilized eomponent (s/w) and the rotational correlation time(τ_e) were calculated on the basis of ESR spectra. From the varying of the s/w and τ_c withthe ehain lengths of spilt labels it was deducted that the binding sites of sulfhydrylgroups on V_79 and V_79-B_1 membrane proteins were of eonical shape and that the binding sitesof sulfhydryl groups on V_79 membrane protein were deeper and narrower than those on V_79-B_1.