Entropic stabilization of isolated beta-sheets.
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.
Dugourd
Philippe
P
Laboratoire de Spectrométrie Ionique et Moléculaire, UMR No. 5579, CNRS et Université Lyon 1, 43 bd du 11 novembre 1918, 69622 Villeurbanne Cedex, France.
Antoine
Rodolphe
R
Breaux
Gary
G
Broyer
Michel
M
Jarrold
Martin F
MF
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*
D010455:Peptides; D014364:Tryptophan; D000409:Alanine