title: Pressure-tuning FT-IR spectroscopic study on the helix-coil transition of Ala-rich oligopeptide in aqueous solution.
abstract: We investigated the effect of pressure on the helix-coil transition of an Ala-rich peptide (AK16: YGAAKAAAAKAAAAKA-NH(2)) in aqueous solution by FT-IR spectroscopy. The spectra of the amide I' region of AK16 in aqueous solution was decomposed into some component bands using a curve fitting method. The peak at around 1635 cm(-1) corresponding to the solvent exposed alpha-helix conformer increases with increasing pressures, while the peak at around 1655 cm(-1) corresponding to the random coil conformer decreases. From the pressure dependence of the band intensities, we determined the volume change from the alpha-helix to random coil conformers of AK16 to be +10.5+/-0.3 cm(3)/mol. The positive volume change is different from the negative volume change generally observed in the pressure denaturation of proteins.
authors.affiliation: Department of Applied Chemistry, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Takekiyo
authors.forename: Akio
authors.initials: A
authors.lastname: Shimizu
authors.forename: Minoru
authors.initials: M
authors.lastname: Kato
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Taniguchi
mesh_terms: D000409:Alanine / Q000737:chemistry; D000595:Amino Acid Sequence; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D011312:Pressure; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water
chemical_list: D009842:Oligopeptides; D014867:Water; D000409:Alanine