title: Solution structure of deltorphin I at 265 K: a quantitative NMR study.
abstract: 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.
authors.affiliation: Istituto Chimica M.I.B del CNR, Arco Felice, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Amodeo
authors.forename: A
authors.initials: A
authors.lastname: Motta
authors.forename: T
authors.initials: T
authors.lastname: Tancredi
authors.forename: S
authors.initials: S
authors.lastname: Salvadori
authors.forename: R
authors.initials: R
authors.lastname: Tomatis
authors.forename: D
authors.initials: D
authors.lastname: Picone
authors.forename: G
authors.initials: G
authors.lastname: Saviano
authors.forename: P A
authors.initials: PA
authors.lastname: Temussi
mesh_terms: 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
chemical_list: D004723:Endorphins; D007211:Indoles; D009842:Oligopeptides; D012996:Solutions; C059567:deltorphin