Dependence of ethanol effects on protein charges.

Ethanol is used as a conventional disinfectant solution. It is highly effective against enveloped viruses due to its effects on virus membranes. It also confers inactivation of non-enveloped viruses, which can be ascribed to conformational changes or changes in association state of the viral proteins induced by ethanol. We have examined here the effects of pH and hence the charged state of proteins on the ethanol-induced conformational changes and self-association of model proteins, i.e., bovine serum albumin (BSA) and ribonuclease A (RNase A). Both proteins showed qualitatively different aggregation behavior and structure changes by ethanol at pH 4.0 and 7.0, at which BSA has opposite charges and RNase A has different degree of net positive charges.