1iq9
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(New page: 200px<br /><applet load="1iq9" size="450" color="white" frame="true" align="right" spinBox="true" caption="1iq9, resolution 1.8Å" /> '''crystal structure at ...)
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Revision as of 15:27, 20 November 2007
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crystal structure at 1.8 A of toxin a from Naja nigricollis venom
Overview
Animal toxins are small proteins built on the basis of a few disulfide, bonded frameworks. Because of their high variability in sequence and, biologic function, these proteins are now used as templates for protein, engineering. Here we report the extensive characterization of the, structure and dynamics of two toxin folds, the "three-finger" fold and the, short alpha/beta scorpion fold found in snake and scorpion venoms, respectively. These two folds have a very different architecture; the, short alpha/beta scorpion fold is highly compact, whereas the, "three-finger" fold is a beta structure presenting large flexible loops., First, the crystal structure of the snake toxin alpha was solved at 1.8-A, resolution. Then, long molecular dynamics simulations (10 ns) in water, boxes of the snake toxin alpha and the scorpion charybdotoxin were, performed, starting either from the crystal or the solution structure. For, both proteins, the crystal structure is stabilized by more hydrogen bonds, than the solution structure, and the trajectory starting from the X-ray, structure is more stable than the trajectory started from the NMR, structure. The trajectories started from the X-ray structure are in, agreement with the experimental NMR and X-ray data about the protein, dynamics. Both proteins exhibit fast motions with an amplitude correlated, to their secondary structure. In contrast, slower motions are essentially, only observed in toxin alpha. The regions submitted to rare motions during, the simulations are those that exhibit millisecond time-scale motions., Lastly, the structural variations within each fold family are described., The localization and the amplitude of these variations suggest that the, regions presenting large-scale motions should be those tolerant to large, insertions or deletions.
About this Structure
1IQ9 is a Single protein structure of sequence from Naja nigricollis with SO4 as ligand. Full crystallographic information is available from OCA.
Reference
Motions and structural variability within toxins: implication for their use as scaffolds for protein engineering., Gilquin B, Bourgoin M, Menez R, Le Du MH, Servent D, Zinn-Justin S, Menez A, Protein Sci. 2003 Feb;12(2):266-77. PMID:12538890
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