title: Entropic stabilization of isolated beta-sheets.
abstract: Temperature-dependent electric deflection measurements have been performed for a series of unsolvated alanine-based peptides (Ac-WA(n)-NH(2), where Ac = acetyl, W = tryptophan, A = alanine, and n = 3, 5, 10, 13, and 15). The measurements are interpreted using Monte Carlo simulations performed with a parallel tempering algorithm. Despite alanine's high helix propensity in solution, the results suggest that unsolvated Ac-WA(n)-NH(2) peptides with n > 10 adopt beta-sheet conformations at room temperature. Previous studies have shown that protonated alanine-based peptides adopt helical or globular conformations in the gas phase, depending on the location of the charge. Thus, the charge more than anything else controls the structure.
authors.affiliation: Laboratoire de Spectrométrie Ionique et Moléculaire, UMR No. 5579, CNRS et Université Lyon 1, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Antoine
authors.forename: Gary
authors.initials: G
authors.lastname: Breaux
authors.forename: Michel
authors.initials: M
authors.lastname: Broyer
authors.forename: Martin F
authors.initials: MF
authors.lastname: Jarrold
mesh_terms: D000409:Alanine / Q000737:chemistry*; D000465:Algorithms; D003198:Computer Simulation; D008958:Models, Molecular; D009010:Monte Carlo Method; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013816:Thermodynamics; D014364:Tryptophan / Q000737:chemistry*
chemical_list: D010455:Peptides; D014364:Tryptophan; D000409:Alanine