title: 17O NMR and FT-IR study of the ionization state of peptides in aprotic solvents. Application to Leu-enkephalin.
abstract: The ionization state of Leu-enkephalin in DMSO and MeCN/DMSO (4/1) solution was studied by the combined use of 17O NMR and FT-IR spectroscopy. After lyophilization of an aqueous solution at nearly neutral pH, Leu-enkephalin essentially exists in the uncharged state in MeCN/DMSO (4/1) solution. In pure DMSO, only 40% of the Leu-enkephalin molecules are in the zwitterionic state under the same conditions.
authors.affiliation: Department of Chemistry, University of Ioannina, Greece.
authors.forename: I P
authors.initials: IP
authors.lastname: Gerothanassis
authors.forename: N
authors.initials: N
authors.lastname: Birlirakis
authors.forename: T
authors.initials: T
authors.lastname: Karayannis
authors.forename: V
authors.initials: V
authors.lastname: Tsikaris
authors.forename: M
authors.initials: M
authors.lastname: Sakarellos-Daitsiotis
authors.forename: C
authors.initials: C
authors.lastname: Sakarellos
authors.forename: B
authors.initials: B
authors.lastname: Vitoux
authors.forename: M
authors.initials: M
authors.lastname: Marraud
mesh_terms: D000595:Amino Acid Sequence; D004121:Dimethyl Sulfoxide; D004743:Enkephalin, Leucine / Q000737:chemistry*; D005583:Fourier Analysis; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D012997:Solvents
chemical_list: D010455:Peptides; D012997:Solvents; D004743:Enkephalin, Leucine; D004121:Dimethyl Sulfoxide