title: [Determination of the local structure of the protein insectotoxin I5A from the scorpion Buthus eupeus from 1H-NMR spectroscopy data].
abstract: The local structure (torsion angles phi, psi and chi 1 of amino acid residues) of insectotoxin I5A (35 residues) of scorpion Buthus eupeus has been determined from cross-peak integral intensities in two-dimensional nuclear Overhauser enhancement (NOESY) spectra and spin coupling constants of vicinal H--NC alpha--H and H--C alpha C beta--H protons. The local structure determination was carried out by fitting complete relaxation matrix of peptide unit protons (protons of a given residue and NH proton of the next residue in the amino acid sequence) with experimental NOESY cross-peak intensities. The obtained intervals of backbone torsional angles phi and psi consistent with NMR data were determined for all but Gly residues. The predominant C alpha--C beta rotamer of the side chain has been unambiguously determined for 42% of the insectotoxin amino acid residues whereas for another 46% residues experimental data are fitted equally well with two rotamers. Stereospecific assignments were obtained for 38% of beta-methylene groups. The determined torsional angles phi, psi and chi 1 correspond to the sterically allowed conformations of the amino acid residues and agree with the insectotoxin secondary structure established earlier by 1H NMR spectroscopy.
authors.forename: A L
authors.initials: AL
authors.lastname: Lomize
authors.forename: A S
authors.initials: AS
authors.lastname: Arsen'ev
authors.forename: I V
authors.initials: IV
authors.lastname: Maslennikov
authors.forename: V F
authors.initials: VF
authors.lastname: Bystrov
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D012604:Scorpion Venoms / Q000737:chemistry*; D014118:Toxins, Biological / Q000737:chemistry*
chemical_list: D000596:Amino Acids; D012604:Scorpion Venoms; D014118:Toxins, Biological; C068292:insectotoxin I5A
vernacular_title: Opredelenie lokal'noĭ struktury belkovogo insektotoksina I5A skorpiona Buthus eupeus po dannym spektroskopii 1H-IaMR.