Demixing of water and ethanol causes conformational redistribution and gelation of the cationic GAG tripeptide

Abstract

The cationic tripeptide GAG undergoes three conformational changes in binary mixtures of water and ethanol. At 17 mol% of ethanol conformational sampling is shifted from pPII towards β-strands. A more pronounced shift in the same direction occurs at 40 mol%. At ca. 55 mol% of ethanol and above a peptide concentration of ca. 0.2 M the ternary peptide–water–ethanol mixture forms a hydrogel which is comprised of unusually large crystalline like non-β sheet fibrils forming a sample spanning matrix.