Solution structure of endothelin-3 determined using NMR spectroscopy

Abstract

The aqueous solution structure of the 21-residue vasoactive peptide hormone endothelin-3 has been determined using high-resolution NMR spectroscopy. A total of 177 proton-proton distance measurements and 5 chi 1 dihedral angle constraints derived from NMR spectra were used to calculate the structure using a combination of distance geometry and dynamical simulated annealing calculations. The calculations reveal a highly ordered, compact conformation in which a helical region extending from K9 to C15 lies in close apposition with the C-terminal hexapeptide; this interaction seems to be largely driven by hydrophobic interactions. Structure-activity studies are interpreted in terms of the conformational features of the calculated endothelin-3 structure.

1H NMR Studies of Sarafotoxin SRTb, a Nonselective Endothelin Receptor Agonist, and IRL 1620, an ETB Receptor-Specific Agonist

“…As the temperature was further increased to 293 and 297 K, however, the absolute ellipticity at 195 nm decreased. Sedimentation equilibrium experiments showed that the peptide remained (Andersen et al, 1992a), and ET3 (solid bars) (Mills et al, 1992), from the values observed in random coil peptides.…”

Tertiary structure of endothelin-1 in water by 1H NMR and molecular dynamics studies

“…The correlation time measurements gave an average molecular volume consistent with monomeric species. The tertiary structure at neutral pH is that of a compact molecule, in which the C-terminal of the peptide folds back toward the a-helical segment (residues [9][10][11][12][13][14][15][16], in close proximity to the pro-R methyl group of Va112, as defined by important NOES involving residues 17-21 and the a-helical core residues 9-14. The results are in agreement with the deuterium exchange experiments, which confirm the existence of a hydrophobic region also at the site of the C-terminal residues 19-21. Since the first report of Yanagisawa et a/.'…”

Does the solid‐state structure of endothelin‐1 provide insights concerning the solution‐state conformational equilibrium?

“…An extensive web of i/i+ 3 NOEs appears from residues 9 through 16 in all published NMR studies in mixed aqueous media. Such NOE connectivities are particularly dense and tight between Lys 9 and Val ~2 and these are not notably co-solvent dependent; for ET-3 at pH 3.6 in the absence of co-solvents, Mills et al [22] report seven through-space contacts between these two key residues, all presumably -< 4.5 A. Pertinent NOE distance constraints used to derive the structure of ET-1 in aqueous ethylene glycol [9] are given in Table 1.…”

“…Chemical shift data reported in nine papers [7][8][9]13,15,16,18,19,22], and in the Ph.D. thesis of C. Chen (University of Washington, 1992) were re-examined for concordance with 2D spectral figures appearing in the same reports; a few minor typographic errors and misattributions were corrected. In the present study, the shifts are converted to chemical shift indices (CSI histograms) by subtracting 'random coil' reference shifts from the reported or corrected values.…”