17O NMR and FT-IR study of the ionization state of peptides in aprotic solvents. Application to Leu-enkephalin.
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.
Gerothanassis
I P
IP
Department of Chemistry, University of Ioannina, Greece.
Birlirakis
N
N
Karayannis
T
T
Tsikaris
V
V
Sakarellos-Daitsiotis
M
M
Sakarellos
C
C
Vitoux
B
B
Marraud
M
M
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
D010455:Peptides; D012997:Solvents; D004743:Enkephalin, Leucine; D004121:Dimethyl Sulfoxide