title: Solvent-induced conformational changes in cyclic peptides: a vibrational circular dichroism study.
abstract: The three-dimensional structure of a peptide is strongly influenced by its solvent environment. In the present study, we study three cyclic tetrapeptides which serve as model peptides for β-turns. They are of the general structure cyclo(Boc-Cys-Pro-X-Cys-OMe) with the amino acid X being either glycine (1), or L- or D-leucine (L- or D-2). Using vibrational circular dichroism (VCD) spectroscopy, we confirm previous NMR results which showed that D-2 adopts predominantly a βII turn structure in apolar and polar solvents. Our results for L-2 indicate a preference for a βI structure over βII. With increasing solvent polarity, the preference for 1 is shifted from βII towards βI. This conformational change goes along with the breaking of an intramolecular hydrogen bond which stabilizes the βII conformation. Instead, a hydrogen bond with a solvent molecule can stabilize the βI turn conformation.
authors: Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G2G2, Canada. yunjie.xu@ualberta.ca.
authors: Christian
authors: C
authors: Merten
authors: Fee
authors: F
authors: Li
authors: Kenny
authors: K
authors: Bravo-Rodriguez
authors: Elsa
authors: E
authors: Sanchez-Garcia
authors: Yunjie
authors: Y
authors: Xu
authors: Wolfram
authors: W
authors: Sander
mesh_terms: D002942:Circular Dichroism; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D012997:Solvents / Q000737:chemistry; D014732:Vibration
chemical_list: D010456:Peptides, Cyclic; D012997:Solvents