TY - JOUR
T1 - Mechanism of stabilization of helical conformations of polypeptides by water containing trifluoroethanol
AU - Cammers-Goodwin, Arthur
AU - Allen, Thomas J.
AU - Oslick, Sherri L.
AU - McClure, Kim F.
AU - Lee, Janette H.
AU - Kemp, D. S.
PY - 1996/4/3
Y1 - 1996/4/3
N2 - For conjugates Ac-Hel1-Ala(n)-OH, n = 1-6, of the previously characterized reporting, conformational template Ac-Hel1, increases in helicity induced by trifluoroethanol (TFE) in water have been related to a simple function of the peptide length n, yielding the helix propagation constant s(Ala), which increases from 1.0 to 1.5 for χ(TFE) = 0-20 mol%. The per-residue helicity increase is similar to the increase in the state stability induced by TFE in monoamide conjugates Ac-Hel1-NHR. Addition of TFE to water significantly increases the rate of interconversion of s-cis/s-trans amide conformers for Ac-Pro-NHMe, consistent with a significant and selective destabilization of the planar resonance-stabilized amide. In dilute aqueous solution TFE increases helicity by selectively destabilizing amide functions that are solvent exposed, with the consequence that compact conformations such as helices that maximize intramolecular amide-amide hydrogen bonding and minimize amide solvent exposure are selectively favored.
AB - For conjugates Ac-Hel1-Ala(n)-OH, n = 1-6, of the previously characterized reporting, conformational template Ac-Hel1, increases in helicity induced by trifluoroethanol (TFE) in water have been related to a simple function of the peptide length n, yielding the helix propagation constant s(Ala), which increases from 1.0 to 1.5 for χ(TFE) = 0-20 mol%. The per-residue helicity increase is similar to the increase in the state stability induced by TFE in monoamide conjugates Ac-Hel1-NHR. Addition of TFE to water significantly increases the rate of interconversion of s-cis/s-trans amide conformers for Ac-Pro-NHMe, consistent with a significant and selective destabilization of the planar resonance-stabilized amide. In dilute aqueous solution TFE increases helicity by selectively destabilizing amide functions that are solvent exposed, with the consequence that compact conformations such as helices that maximize intramolecular amide-amide hydrogen bonding and minimize amide solvent exposure are selectively favored.
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U2 - 10.1021/ja952900z
DO - 10.1021/ja952900z
M3 - Article
AN - SCOPUS:0030567341
SN - 0002-7863
VL - 118
SP - 3082
EP - 3090
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 13
ER -