1wqc
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An unusual fold for potassium channel blockers : NMR structure of three toxins from the scorpion Opisthacanthus madagascariensis
OverviewOverview
The Om-toxins are short peptides (23-27 amino acids) purified from the, venom of the scorpion Opisthacanthus madagascariensis. Their, pharmacological targets are thought to be potassium channels. Like, Csalpha/beta (cystine-stabilized alpha/beta) toxins, the Om-toxins alter, the electrophysiological properties of these channels; however, they do, not share any sequence similarity with other scorpion toxins. We herein, demonstrate by electrophysiological experiments that Om-toxins decrease, the amplitude of the K+ current of the rat channels Kv1.1 and Kv1.2, as, well as human Kv1.3. We also determine the solution structure of three of, the toxins by use of two-dimensional proton NMR techniques followed by, distance geometry and molecular dynamics. The structures of these three, peptides display an uncommon fold for ion-channel blockers, Csalpha/alpha, (cystine-stabilized alpha-helix-loop-helix), i.e. two alpha-helices, connected by a loop and stabilized by two disulphide bridges. We compare, the structures obtained and the dipole moments resulting from the, electrostatic anisotropy of these peptides with those of the only other, toxin known to share the same fold, namely kappa-hefutoxin1.
About this StructureAbout this Structure
1WQC is a Protein complex structure of sequences from Opisthacanthus madagascariensis. Full crystallographic information is available from OCA.
ReferenceReference
An unusual fold for potassium channel blockers: NMR structure of three toxins from the scorpion Opisthacanthus madagascariensis., Chagot B, Pimentel C, Dai L, Pil J, Tytgat J, Nakajima T, Corzo G, Darbon H, Ferrat G, Biochem J. 2005 May 15;388(Pt 1):263-71. PMID:15631621
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