title: End effects influence short model peptide conformation.
abstract: Previously, we derived a P(II) propensity scale using N- and C-terminally blocked host-guest peptide model AcGGXGGNH(2) (X ≠ Gly) and concluded that P(II) represents a dominant conformation in the majority of this series of 19 peptides (Shi et al. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 17964-17968). Recently, Schweitzer-Stenner and co-workers examined a series of eight short host-guest tripeptides with the sequence GXG (X = A, V, F, S, E, L, M, and K) in which both N- and C-ends were unblocked and reported major differences in P(II) content for F, V, and S compared to our scale (Hagarman et al. J. Am. Chem. Soc. 2010, 132, 540-551). We have investigated four representative amino acids (X = A, V, F, and S) in three series of peptides (GXG, AcGXGNH(2), and AcGGXGGNH(2)) as a function of pH in this study. Our data show that P(II) content in the GXG series (X = A, V, F, and S) is pH-dependent and that the conformations of each amino acid differ markedly between the GXG and AcGXGNH(2)/AcGGXGGNH(2) series. Our results indicate that P(II) scales are sequence and context dependent and the presence of proximal charged end groups exerts a strong effect on P(II) population in short model peptides.
authors.affiliation: School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, PR China.
authors.forename: Liu
authors.initials: L
authors.lastname: He
authors.forename: Abel E
authors.initials: AE
authors.lastname: Navarro
authors.forename: Zhengshuang
authors.initials: Z
authors.lastname: Shi
authors.forename: Neville R
authors.initials: NR
authors.lastname: Kallenbach
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D006863:Hydrogen-Ion Concentration; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D010455:Peptides; C011083:polyproline