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 study the properties of binding sites of sulfhydryl groups on the membrane proteins of normal cell V79 and cancer cells V79-B1 in the lung of Chinese hamster. The ratio of the strongly immobilized component to the weakly immobilized component (s/w) and the rotational correlation time (tau c) were calculated on the basis of ESR spectra. From the varying of the s/w and tau c with the chain lengths of spin labels it was deducted that the binding sites of sulfhydryl groups on V79 and V79-B1 membrane proteins were of conical shape and that the binding sites of sulfhydryl groups on V79 membrane protein were deeper and narrower than those on V79-B1.