1bah
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(New page: 200px<br /><applet load="1bah" size="450" color="white" frame="true" align="right" spinBox="true" caption="1bah" /> '''A TWO DISULFIDE DERIVATIVE OF CHARYBDOTOXIN ...)
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Revision as of 09:23, 20 November 2007
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A TWO DISULFIDE DERIVATIVE OF CHARYBDOTOXIN WITH DISULFIDE 13-33 REPLACED BY TWO ALPHA-AMINOBUTYRIC ACIDS, NMR, 30 STRUCTURES
Overview
The alpha/beta scorpion fold consisting of a short alpha-helix and, beta-sheet is a structural motif common to scorpion toxins, insect, defensins, and plant gamma-thionins that invariably contains three, disulfides. CHABII is a two-disulfide derivative of the scorpion toxin, charybdotoxin (ChTX), chemically synthesized by inserting two, L-alpha-aminobutyric acids in place of the two half-cystine residues, involved in the disulfide 13-33. This disulfide is one of the two, disulfides which connect the alpha-helix to the beta-sheet. The solution, structure of CHABII was determined at pH 6.3 and 5 degrees C using 2D NMR, and simulated annealing from 513 distance and 46 dihedral angle, constraints. The NMR structure of CHABII is well-defined as judged from, the low value of the averaged backbone rms deviation between the 30 lowest, energy structures and the energy-minimized mean structure ((rmsd) = 0.65 A, for the entire sequence and 0.48 A for the segment 3-36). Analysis and, comparison of the solution structures of CHABII and ChTX lead to the, following conclusions: (i) the fold of CHABII is similar to that of ChTX, as indicated by the low value of the averaged backbone atomic rms, deviation between the 10 lowest energy solution structures of the two, proteins (1.44 A); (ii) the packing of the hydrophobic core is, well-preserved, underlying the critical structural role of the hydrophobic, interactions even for such a small and cysteine-rich protein as ChTX.
About this Structure
1BAH is a Single protein structure of sequence from Leiurus quinquestriatus. Full crystallographic information is available from OCA.
Reference
NMR solution structure of a two-disulfide derivative of charybdotoxin: structural evidence for conservation of scorpion toxin alpha/beta motif and its hydrophobic side chain packing., Song J, Gilquin B, Jamin N, Drakopoulou E, Guenneugues M, Dauplais M, Vita C, Menez A, Biochemistry. 1997 Apr 1;36(13):3760-6. PMID:9092804
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