title: Conformational studies of alanine-rich peptide using CD and FTIR spectroscopy.
abstract: The circular dichroism (CD) and Fourier transform infrared (FTIR) methods were applied to the conformational studies of alanine-rich peptide Ac-K-[A]11-KGGY-NH2 (where K is lysine, A is alanine, G is glycine and Y is tyrozyne) in water, methanol (MeOH) and trifluoroethanol (TFE). The analysis of CD-spectra of the peptide in water at different concentrations revealed that the secondary structure content depends on the peptide concentration and pH of the solution. The increase of the peptide concentration causes a decrease of alpha-helix content and, simultaneously, an increase of beta-sheet structure, while the unordered structure is the predominant one. Additional elements are discovered in MeOH and TFE but alpha-helix and beta-turns predominate. Moreover, in these solutions the percentage content of the secondary structure does not depend on the temperature. FTIR measurements, carried out at higher peptide concentration (about one order of magnitude) than these CD measurements mentioned above, revealed that in water solution the solid state beta-sheet, and aggregated structures, dominate. However, in TFE the most abundant are alpha-helix and beta-turns structures. The thioflavine T assay showed the tendency of the studied peptide for aggregate.
authors.affiliation: Faculty of Chemistry, University of Gdańsk, Sobieskiego 18/19, 80-952 Gdańsk, Poland.
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Bagińska
authors.forename: Joanna
authors.initials: J
authors.lastname: Makowska
authors.forename: Wiesław
authors.initials: W
authors.lastname: Wiczk
authors.forename: Franciszek
authors.initials: F
authors.lastname: Kasprzykowski
authors.forename: Lech
authors.initials: L
authors.lastname: Chmurzyński
mesh_terms: D000409:Alanine / Q000737:chemistry*; D002942:Circular Dichroism / Q000379:methods*; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D014270:Trifluoroethanol / Q000737:chemistry
chemical_list: D010455:Peptides; D014270:Trifluoroethanol; D000409:Alanine