Solution structure of deltorphin I at 265 K: a quantitative NMR study.
Deltorphin I, a delta-selective opioid peptide, has been studied in a DMSOd6/H2O cryoprotective mixture by two-dimensional (2D) NMR spectroscopy in the temperature range 260 K to 305 K. The high viscosity of the solvent at low temperature mimics a distinctive physico-chemical feature of cytoplasm and allows the measurement of a NOESY spectrum rich in intra- and inter-residue effects. Backbone NOEs at 265 K can be calculated with good accuracy in terms of only two limiting conformers: one folded, with a mole fraction of 0.30, and another extended with a mole fraction of 0.70. This calculation is still a rough approximation of the complex conformational equilibria existing in solution but, to the best of our knowledge, is the first one for a flexible peptide, and represents an encouraging starting point for a quantitative evaluation of NMR data of small, flexible peptides in solution. The folded conformer consistent with observed NOEs has a shape surprisingly similar to those of unrelated, rigid, delta-selective opiates.
Amodeo
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P
Istituto Chimica M.I.B del CNR, Arco Felice, Italy.
Motta
A
A
Tancredi
T
T
Salvadori
S
S
Tomatis
R
R
Picone
D
D
Saviano
G
G
Temussi
P A
PA
D000595:Amino Acid Sequence; D004723:Endorphins / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry
D004723:Endorphins; D007211:Indoles; D009842:Oligopeptides; D012996:Solutions; C059567:deltorphin