2-DIMENSIONAL H-1-NMR STUDY OF THE SPATIAL STRUCTURE OF NEUROTOXIN-IIFROM NAJA-NAJA-OXIANA

The spatial structure of neurotoxin II from the venom of the central A sian cobra Naja naja oxiana was determined by two-dimensional H-1-NMR techniques and computational analysis. Nearly complete proton resonanc e assignments for 61 amino acid residues have been made using two-dime nsional (2D) homonuclear total correlated spectroscopy, 2D homonuclear double-quantum-filtered correlated spectroscopy and 2D homonuclear NO E spectroscopy (NOESY) experiments. The cross-peak volumes in NOESY sp ectra spin-spin coupling constants of vicinal protons NH-CalphaH and C alphaH-CbetaH and the observation of slow deuterium exchange of amide protons were used to define local structure and a set of constraints f or distance geometry program DIANA. The average root-mean-square devia tions are 5 3 pm for backbone heavy atoms and 11 8 pm for all heavy at oms of 19 final neurotoxin II conformations. The spatial structure is characterized by a short double-stranded (residues 1-5 and 13-17) and a triple-stranded (residues 22-30, 33-41 and 50-54) antiparallel beta- sheets.