Interaction between Proteins and Synthetic Detergents

Attempts have been made to explain the action of certain proteindenaturing agents, such as organic solvents, urea, guanidine halides, and salicylates, in terms of (a) physical solvent effects (cf. (4)) or (b) unspecified intermediary combination between denaturant and protein (cf. (5)). Recent work has shown that the denaturing effect of guanidine hydrochloride, one of the most powerful denaturants hitherto known, is equaled by that of synthetic detergents and that the latter are effective in considerably lower concentrations (6-8). Chemical and electrophoretic measurements have revealed the formation of stoichiometric complexes of horse serum albumin and sodium dodecyl sulfate (SDS), presumably involving the ionized basic groups of the protein molecule (1, 2,9). This view is further supported by viscosity and diffusion measurements on serum albumin-SDS mixtures presented in this paper. It is proposed that combination of SDS with specific side chain groups of the protein is an important step in denaturation.