Circular dichroism and UV resonance raman study of the impact of alcohols on the Gibbs free energy landscape of an alpha-helical peptide.
We used CD and UV resonance Raman spectroscopy to study the impact of alcohols on the conformational equilibria and relative Gibbs free energy landscapes along the Ramachandran Psi-coordinate of a mainly poly-Ala peptide, AP with an AAAAA(AAARA)(3)A sequence. 2,2,2-Trifluoroethanol (TFE) most stabilizes the alpha-helix-like conformations, followed by ethanol, methanol, and pure water. The pi-bulge conformation is stabilized more than the alpha-helix, while the 3(10)-helix is destabilized due to the alcohol-increased hydrophobicity. Turns are also stabilized by alcohols. We also found that while TFE induces more alpha-helices, it favors multiple, shorter helix segments.
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Kan
K
Xiong
Sanford A
SA
Asher
D000438:Alcohols / Q000494:pharmacology*; D000595:Amino Acid Sequence; D002942:Circular Dichroism; D000431:Ethanol / Q000494:pharmacology; D007202:Indicators and Reagents; D000432:Methanol / Q000494:pharmacology; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry* / Q000187:drug effects; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
D000438:Alcohols; D007202:Indicators and Reagents; D010455:Peptides; D014867:Water; D000431:Ethanol; D000432:Methanol