1cn2
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(New page: 200px<br /><applet load="1cn2" size="450" color="white" frame="true" align="right" spinBox="true" caption="1cn2" /> '''SOLUTION STRUCTURE OF TOXIN 2 FROM CENTRUROI...)
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Revision as of 10:28, 20 November 2007
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SOLUTION STRUCTURE OF TOXIN 2 FROM CENTRUROIDES NOXIUS HOFFMANN, A BETA SCORPION NEUROTOXIN ACTING ON SODIUM CHANNELS, NMR, 15 STRUCTURES
Overview
We have determined the solution structure of Cn2, a beta-toxin extracted, from the venom of the New World scorpion Centruroides noxius Hoffmann. Cn2, belongs to the family of scorpion toxins that affect the sodium channel, activity, and is very toxic to mammals (LD50=0.4 microg/20 g mouse mass)., The three-dimensional structure was determined using 1H-1H two-dimensional, NMR spectroscopy, torsion angle dynamics, and restrained energy, minimization. The final set of 15 structures was calculated from 876, experimental distance constraints and 58 angle constraints. The structures, have a global r. m.s.d. of 1.38 A for backbone atoms and 2.21 A for all, heavy atoms. The overall fold is similar to that found in the other, scorpion toxins acting on sodium channels. It is made of a triple-stranded, antiparallel beta-sheet and an alpha-helix, and is stabilized by four, disulfide bridges. A cis-proline residue at position 59 induces a kink of, the polypeptide chain in the C-terminal region. The hydrophobic core of, the protein is made up of residues L5, V6, L51, A55, and by the eight, cysteine residues. A hydrophobic patch is defined by the aromatic residues, Y4, Y40, Y42, W47 and by V57 on the side of the beta-sheet facing the, solvent. A positively charged patch is formed by K8 and K63 on one edge of, the molecule in the C-terminal region. Another positively charged spot is, represented by the highly exposed K35. The structure of Cn2 is compared, with those of other scorpion toxins acting on sodium channels, in, particular Aah II and CsE-v3. This is the first structural report of an, anti-mammal beta-scorpion toxin and it provides the necessary information, for the design of recombinant mutants that can be used to probe, structure-function relationships in scorpion toxins affecting sodium, channel activity.
About this Structure
1CN2 is a Single protein structure of sequence from Centruroides noxius with NH2 as ligand. Full crystallographic information is available from OCA.
Reference
Solution structure of toxin 2 from centruroides noxius Hoffmann, a beta-scorpion neurotoxin acting on sodium channels., Pintar A, Possani LD, Delepierre M, J Mol Biol. 1999 Mar 26;287(2):359-67. PMID:10080898
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