1lqi

<StructureSection load='1lqi' size='340' side='right'caption='[[1lqi]], [[NMR_Ensembles_of_Models | 29 NMR models]]' scene=''>

<table><tr><td colspan='2'>[[1lqi]] is a 1 chain structure with sequence from [http://en.wikipedia.org/wiki/Leiqh Leiqh]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1LQI OCA]. For a <b>guided tour on the structure components</b> use [http://proteopedia.org/fgij/fg.htm?mol=1LQI FirstGlance]. <br>

</td></tr><tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[1lqh|1lqh]]</div></td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">POTENTIAL ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=6884 LEIQH])</td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://proteopedia.org/fgij/fg.htm?mol=1lqi FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1lqi OCA], [http://pdbe.org/1lqi PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1lqi RCSB], [http://www.ebi.ac.uk/pdbsum/1lqi PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1lqi ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/SCXA_LEIQH SCXA_LEIQH]] Alpha toxins bind voltage-independently at site-3 of sodium channels (Nav) and inhibit the inactivation of the activated channels, thereby blocking neuronal transmission. The dissociation is voltage-dependent. This toxin is active on insects. It is also highly toxic to crustaceans and has a measurable but low toxicity to mice.

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== Publication Abstract from PubMed ==

The solution structure of a recombinant active alpha-neurotoxin from Leiurus quinquestriatus hebraeus, Lqh(alpha)IT, was determined by proton two-dimensional nuclear magnetic resonance spectroscopy (2D NMR). This toxin is the most insecticidal among scorpion alpha-neurotoxins and, therefore, serves as a model for clarifying the structural basis for their biological activity and selective toxicity. A set of 29 structures was generated without constraint violations exceeding 0.4 A. These structures had root mean square deviations of 0.49 and 1.00 A with respect to the average structure for backbone atoms and all heavy atoms, respectively. Similarly to other scorpion toxins, the structure of Lqh(alpha)IT consists of an alpha-helix, a three-strand antiparallel beta-sheet, three type I tight turns, a five-residue turn, and a hydrophobic patch that includes tyrosine and tryptophan rings in a "herringbone" arrangement. Positive phi angles were found for Ala50 and Asn11, suggesting their proximity to functionally important regions of the molecule. The sample exhibited conformational heterogeneity over a wide range of experimental conditions, and two conformations were observed for the majority of protein residues. The ratio between these conformations was temperature-dependent, and the rate of their interconversions was estimated to be on the order of 1-5 s(-1) at 308 K. The conformation of the polypeptide backbone of Lqh(alpha)IT is very similar to that of the most active antimammalian scorpion alpha-toxin, AaHII, from Androctonus australis Hector (60% amino acid sequence homology). Yet, several important differences were observed at the 5-residue turn comprising residues Lys8-Cys12, the C-terminal segment, and the mutual disposition of these two regions. 2D NMR studies of the R64H mutant, which is 3 times more toxic than the unmodified Lqh(alpha)IT, demonstrated the importance of the spatial orientation of the last residue side chain for toxicity of Lqh(alpha)IT.

Solution structures of a highly insecticidal recombinant scorpion alpha-toxin and a mutant with increased activity.,Tugarinov V, Kustanovich I, Zilberberg N, Gurevitz M, Anglister J Biochemistry. 1997 Mar 4;36(9):2414-24. PMID:9054546<ref>PMID:9054546</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

<references/>

[[Category: Leiqh]]

[[Category: Anglister, J]]

[[Category: Gurevitz, M]]

[[Category: Kustanovich, I]]

[[Category: Tugarinov, V]]

[[Category: Zilberberg, N]]

[[Category: Sodium channel inhibitor]]