Tryptophan phosphorescence study of the influence of detergents on the internal dynamics of human erythrocyte membrane proteins

Abstract

Room-temperature tryptophan phosphorescence was used to assess the slow (millisecond) internal dynamics of proteins in isolated human erythrocyte membranes under the action of detergents: dodecylsulfate, lauroyl sarcosinate, deoxycholate, digitonin, and Tween 20 (concentrations varied from 0.01 to 6 mM). All detergents markedly enhanced the slow internal dynamics, but the dose-response patterns were specific for each agent. The aggregate data support the idea that the slow internal dynamics is restricted in membrane proteins relative to soluble proteins mostly because of intramembrane protein association and isolation from the aqueous milieu, with a possible contribution of a more rigid secondary structure.