Energy landscape of a beta-hairpin peptide in explicit water studied by multicanonical molecular dynamics

A beta -hairpin peptide [Ace-Ile-Thr-Val-Asn-Gly-Lys-Thr-Tyr-Nme] in explic it water was studied with multicanonical molecular dynamics simulation. The obtained energy landscape was separated into two regions: deep energy well s and rugged surface. The deep wells consisted of beta -hairpin conformatio ns with different hydrogen-bonding patterns, and the rugged surface had ran dom-coils. Both the random-coil and the beta -hairpins were stable at 300 K . A mechanism was proposed for the beta -hairpin formation: non-oriented th ermal fluctuation drives the peptide from the random-coil to a beta -hairpi n. where the beta -turn is formed but the strand is partially disordered. T his P-hairpin can switch to a different beta -hairpin, where the strand is ordered but the beta -turn is disordered. (C) 2001 Elsevier Science B.V. Al l rights reserved.