1b7d: Difference between revisions

[[Image:1b7d.gif|left|200px]]<br /><applet load="1b7d" size="350" color="white" frame="true" align="right" spinBox="true"  

The crystal structure of neurotoxin Ts1, a major component of the venom of the Brazilian scorpion Tityus serrulatus, has been determined at 1.7 A resolution. It is the first X-ray structure of a highly toxic anti-mammalian beta-toxin. The folding of the polypeptide chain of Ts1 is similar to that of other scorpion toxins. A cysteine-stabilised alpha-helix/beta-sheet motif forms the core of the flattened molecule. All residues identified as functionally important by chemical modification and site-directed mutagenesis are located on one side of the molecule, which is therefore considered as the Na+channel recognition site. The distribution of charged and non-polar residues over this surface determines the specificity of the toxin-channel interaction. Comparison to other scorpion toxins shows that positively charged groups at positions 1 and 12 as well as a negative charge at position 2 are likely determinants of the specificity of beta-toxins. In contrast, the contribution of the conserved aromatic cluster to the interaction might be relatively small. Comparison of Ts1 to weak beta-toxins from Centruroides sculpturatus Ewing reveals that a number of basic amino acid residues located on the face of the molecule opposite to the binding surface may account for the high toxicity of Ts1.

1B7D is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Tityus_serrulatus Tityus serrulatus] with <scene name='pdbligand=PO4:'>PO4</scene> as [http://en.wikipedia.org/wiki/ligand ligand]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1B7D OCA].  

[[Category: Jr., M S.Sanches.]]

[[Category: Toyama, M H.]]

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