A role of the Trp–His interaction in the conformational switch between α-helix and β-sheet in short alanine-based peptides

Abstract

The interaction between aromatic residues (Trp, Tyr, and Phe) and a histidine residue (His) is often present in proteins and plays an important role in determining the conformation of peptides and the folding of globular proteins. The role of the Trp–His interaction in the conformation of peptides and the folding of globular proteins has been investigated for a series of alanine-based peptides having a pair of Trp–His in different geometrical spacing and positions. A conformational switch between the α-helix and β-sheet due to the Trp–His interaction was found with the result that the pairs of Trp–His with (i, i + 4) and (i, i + 2) spacing at the C terminus led to α-helix and β-sheet conformations, respectively. The possible factors contributing to the positional effect of the Trp–His interaction are also discussed in the paper. The role of the Trp–His interaction in the conformational switch between the α-helix and β-sheet in peptides is important in the evolution of new protein folding by accumulations of simple mutations in peptides and proteins.