1lsi
From Proteopedia
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LSIII (NMR, 23 STRUCTURES)
Overview
We report the sequence-specific proton assignments and solution structure, of the long neurotoxin LSIII from the venom of Laticauda semifasciata, determined by two- and three-dimensional 1H NMR. Input for structure, calculations consisted of 497 NOE-derived distance restraints and 45, dihedral angle restraints obtained from J couplings. A, two-particle-per-residue representation of protein structure was used to, generate 200 initial structures which were then subjected to all-atom, refinement by simulated annealing. Twenty-three final structures, consistent with the experimental restraints were obtained; the average, atomic RMS difference between the individual structures and the mean, structure was 0.82 A for the backbone heavy atoms and 1.3 A for all heavy, atoms (residues 1-26, 37-60). The main elements of regular secondary, structure are a three-stranded antiparallel beta-sheet and three, finger-like loops protruding from a globular core, consistent with, previously reported structures of long neurotoxins. The end of the, prominent loop II, which is involved in binding to acetylcholine receptor, is disordered relative to the rest of the molecule. A novel finding of, this study is that the loop has a well defined local structure; this and, other observations suggest this region moves as a rigid body. We propose, that this motion is a heretofore unrecognized general feature of long, neurotoxins, with specific consequences for binding to the acetylcholine, receptor.
About this Structure
1LSI is a Single protein structure of sequence from Laticauda semifasciata. Full crystallographic information is available from OCA.
Reference
Solution structure of LSIII, a long neurotoxin from the venom of Laticauda semifasciata., Connolly PJ, Stern AS, Hoch JC, Biochemistry. 1996 Jan 16;35(2):418-26. PMID:8555211
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