Conformational features of disulfide intact and reduced forms of hen egg white lysozyme in aqueous solution in the presence of trifluoroethanol (TFE): Implications for protein folding intermediates

Abstract

The conformational features of reduced and disulfide intact hen egg white lysozyme in aqueous 2,2,2-trifluoroethanol (TFE) solutions have been examined using circular dichroism and fluorescence spectroscopies. We find that non-native like and molten globule like states are induced in reduced lysozyme, with non-native like and native like α helicities and with reduced accessibility of tryptophans to collisional quencher acrylamide, in the presence of TFE as judged from circular dichroism and fluorescence experiments. We correlate our results to kinetic hydrogen–deuterium exchange NMR results of the refolding of lysozyme available in the literature. We discuss the implications of our results for disulfide bond formation and protein folding intermediates.