Interaction between Protein Sulphydryl Groups and Lipid Double Bonds in Biological Membranes

Abstract

EXPERIMENTS^1,2 using brain microsomes as a model membrane system have demonstrated that membrane permeability is increased and ion discrimination decreased by two classes of compounds: (1) those that react with membrane sulphydryl groups (for example, p-chloromercuribenzoate), and (2) those that initiate peroxidation of membrane lipids (for example, iron plus ascorbic acid). These two classes of compounds are further related by the observations² that lipid peroxidation increases the content of reactive sulphydryl groups in the membrane, whereas agents binding sulphydryl accelerate the onset of lipid peroxidation. Although this relationship between reactive sulphydryl groups and reactive double bonds may be secondary to other factors that are more directly related to increased membrane permeability, it is of interest to consider a possible structural and functional interaction between protein sulphydryl groups and lipid double bonds that could underlie these observations, and that could also be related to physiological and pharmacological membrane events.