The interaction of detergents with bilayer lipid membranes.

Detergents are widely used for extracting and purifying membrane proteins. Four such detergents have been studied to find the extent to which they alone can alter black lipid film conductances. The slope of the plot of conductivity versus concentration for Triton X-100 is 4.54 in the range 0.025--0.15 mM; dodecyl sulphate 0.82 in the range 0.01--1 mM; sodium deoxycholate 1.03 in the range 0.01--1 mM and sodium cholate 1.37 in the range 0.1--10 mM. These ranges are below the respective critical micelle concentrations; above these concentrations the membranes break. Bilayer lipid membrane conductivity measured at constant detergent concentration increases with the conductivity of the bathing salt solution with a slope greater than 1, indicating an effect on the putative pore structures induced by detergents.