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1jza
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(New page: 200px<br /><applet load="1jza" size="450" color="white" frame="true" align="right" spinBox="true" caption="1jza, resolution 2.20Å" /> '''Crystal Structure of...)
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Revision as of 16:35, 20 November 2007
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Crystal Structure of Variant 2 Scorpion Toxin from Centruroides sculpturatus Ewing
Overview
Centruroides sculpturatus Ewing variant 2 toxin (CsE-v2) is a neurotoxin, isolated from the venom of a scorpion native to the Arizona desert. The, structure of CsE-v2 was solved in two different crystal forms using a, combination of molecular replacement and multiple isomorphous replacement, techniques. Crystals of CsE-v2 display a temperature-dependent, reversible-phase transition near room temperature. At lower temperature, the space group changes from P3(2)21 to P3(1)21 with an approximate, doubling of the C-axis. The small-cell structure, which has one molecule, per asymmetric unit, has an R factor of 0.229 at 2.8 A resolution. The, large-cell structure has two molecules per asymmetric unit and was refined, at 2.2 A resolution to an R factor of 0.255. CsE-v2 is a rigid, compact, structure with four intrachain disulfide bonds. The structure is similar, to other long-chain beta neurotoxins, and the largest differences occur in, the last six residues. The high-resolution structure of CsE-v2 corrects an, error in the reported C-terminal sequence; the terminal tripeptide, sequence is Ser 64-Cys 65-Ser 66 rather than Ser 64-Ser 65-Cys 66., Comparison of CsE-v2 with long-chain alpha toxins reveals four insertions, and one deletion, as well as additional residues at the N and C termini., Structural alignment of alpha and beta toxins suggests that the primary, distinguishing feature between the two classes is the length of the loop, between the second and third strands in a three-strand beta sheet. The, shorter loop in alpha toxins exposes a critical lysine side chain, whereas, the longer loop in beta toxins buries the corresponding basic residue, (either arginine or lysine).
About this Structure
1JZA is a Single protein structure of sequence from Centruroides sculpturatus. Full crystallographic information is available from OCA.
Reference
Structure of variant 2 scorpion toxin from Centruroides sculpturatus Ewing., Cook WJ, Zell A, Watt DD, Ealick SE, Protein Sci. 2002 Mar;11(3):479-86. PMID:11847271
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