Formation of β-sheets in glutamine and alanine tripeptides

Abstract

The misfolding and aggregation of proteins is associated with many different diseases including the trinucleotide repeat disorders and Prion diseases. We have studied three residue peptides comprising alanine and glutamine in order to understand the short range interactions affecting the formation of β-rich aggregates. Using infrared spectroscopy, we have found that trialanine and triglutamine form significant amounts of β-sheet, but that tripeptides containing alanine and glutamine are only able to form β-sheet if the glutamine side-chains extend outward on both faces of the sheet. From our data, we conclude that different stabilizing interactions are responsible for β-sheet formation in trialanine and triglutamine.