Thermally denatured proteins: spin label studies of reversal of thermal aggregation of bovine serum albumin (BSA)

Abstract

Suspensions of thermally aggregated SH-modified BSA become optically clear in the presence of SDS, urea or at high pH. In addition, the e.s.r. spectra of spin labelled samples become identical to those obtained from solutions of spin labelled native BSA under the same conditions. These results demonstrate that the aggregation process which occurs on thermal denaturation can be reversed by simple physical means. Similar studies show that a major portion of thermally aggregated unmodified BSA can be dissociated into individual protein molecules.