Formation of β-sheets in glutamine and alanine tripeptides

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 beta-rich aggregates. Using infrared spectroscopy, we have found that trialanine and triglutamine form significant amounts of beta-sheet, but that tripeptides containing alanine and glutamine are only able to form beta-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 beta-sheet formation in trialanine and triglutamine. (C) 2011 Elsevier Inc. All rights reserved.