1nxn
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(New page: 200px<br /><applet load="1nxn" size="450" color="white" frame="true" align="right" spinBox="true" caption="1nxn" /> '''SOLUTION STRUCTURE OF CONTRYPHAN-VN'''<br />...)
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Revision as of 20:31, 20 November 2007
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SOLUTION STRUCTURE OF CONTRYPHAN-VN
Overview
The solution structure of contryphan-Vn, a cyclic peptide with a double, cysteine S-S bridge and containing a D-tryptophan extracted from the venom, of the cone snail Conus ventricosus, has been determined by NMR, spectroscopy using a variety of homonuclear and heteronuclear NMR methods, and restrained molecular dynamics simulations. The main conformational, features of backbone contryphan-Vn are a type IV beta-turn from Gly 1 to, Lys 6 and a type I beta-turn from Lys 6 to Cys 9. As already found in, other contryphans, one of the two prolines--the Pro4--is mainly in the cis, conformation while Pro7 is trans. A small hydrophobic region probably, partly shielded from solvent constituted from the close proximity of side, chains of Pro7 and Trp8 was observed together with a persistent salt, bridge between Asp2 and Lys6, which has been revealed by the diagnostic, observation of specific nuclear Overhauser effects. The salt bridge was, used as a restraint in the molecular dynamics in vacuum but without, inserting explicit electrostatic contribution in the calculations. The, backbone of the unique conformational family found of contryphan-Vn, superimposes well with those of contryphan-Sm and contryphan-R. This, result indicates that the contryphan structural motif represents a robust, and conserved molecular scaffold whose main structural determinants are, the size of the intercysteine loop and the presence and location in the, sequence of the D-Trp and the two Pro residues.
About this Structure
1NXN is a Protein complex structure of sequences from [1] with NH2 as ligand. This structure superseeds the now removed PDB entry 1N3V. Full crystallographic information is available from OCA.
Reference
Solution structure of the cyclic peptide contryphan-Vn, a Ca2+-dependent K+ channel modulator., Eliseo T, Cicero DO, Romeo C, Schinina ME, Massilia GR, Polticelli F, Ascenzi P, Paci M, Biopolymers. 2004 Jun 15;74(3):189-98. PMID:15150794
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