1c4e: Difference between revisions

[[Image:1c4e.jpg|left|200px]]

'''GURMARIN FROM GYMNEMA SYLVESTRE'''

Gurmarin is a 35-residue polypeptide from the Asclepiad vine Gymnema sylvestre. It has been utilised as a pharmacological tool in the study of sweet-taste transduction because of its ability to selectively inhibit the neural response to sweet tastants in rats. We have chemically synthesised and folded gurmarin and determined its three-dimensional solution structure to high resolution using two-dimensional NMR spectroscopy. Structure calculations utilised 612 interproton-distance, 19 dihedral-angle, and 18 hydrogen-bond restraints. The structure is well defined for residues 3-34, with backbone and heavy atom rms differences of 0.27 +/- 0.09 A and 0.73 +/- 0.09 A, respectively. Gurmarin adopts a compact structure containing an antiparallel beta-hairpin (residues 22-34), several well-defined beta-turns, and a cystine-knot motif commonly observed in toxic and inhibitory polypeptides. Despite striking structural homology with delta-atracotoxin, a spider neurotoxin known to slow the inactivation of voltage-gated Na+ channels, we show that gurmarin has no effect on a variety of voltage-sensitive channels.

1C4E is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Gymnema_sylvestre Gymnema sylvestre]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=2gur 2gur]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1C4E OCA].  

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