Solubilization and denaturation of monomeric actin from erythrocyte membranes by p-mercuribenzenesulfonate.

Solutions of p-mercuribenzenesulfonate extract the peripheral proteins from the red cell membrane in a water-soluble form. Low concentrations of the reagent selectively solubilize actin, while at higher concentrations, spectrin, ankyrin and bands 4.2 and 4.1 are extracted. After brief exposure to the reagent, followed by displacement of the mercurial with dithiothreitol or 2-mercaptoethanol, the soluble actin is capable of inhibiting DNAse I activity. With prolonged exposure or with higher concentrations of the reagent, the ability to inhibit DNAse is gradually lost. The kinetics of both the release of actin capable of DNAse inhibition and the subsequent loss of that capability are pseudo-first-order with respect to time, but show second-order dependence on the concentration of mercurial. These data suggest that dissociation of the actin from protofilaments in the cytoskeleton requires exposure of more than one sulfhydryl group to the reagent. Subsequent inactivation also appears to be dependent on the reaction of further multiple sulfhydryl groups, possibly in buried regions of the actin molecule.