title: Development of small molecules that mimic the binding of omega-conotoxins at the N-type voltage-gated calcium channel.
abstract: Cone snails (Conidae) are marine predators with some extraordinary features. Their venom contains a hundred or more peptides that target numerous ion channels and receptors in mammals, including several that are involved in disease. omega-Conotoxins from fish hunting snails are 24-27 residue peptides with a rigid 4-loop cysteine framework that target the N-type voltage-gated calcium channel (VGCC). Two omega-conotoxins, MVIIA and CVID are currently in clinical development for chronic pain management (Ziconotide or Prialt, and AM336, respectively). In an attempt to develop small molecule equivalents of CVID, we defined the Calpha-Cbeta vectors of the residues believed to be important for binding to the N-type VGCC. Using these vectors, we undertook a virtual screening of virtual libraries approach to identify compounds that matched the pharmacophore. Cyclic pentapeptides containing residues of loop 2 of CVID, with one or more being a D-amino acid were designed and synthesised and were found to be active at the N-type VGCC (IC50 approximately 20 microM). Agreeing with the specificity profile of CVID, molecules were inactive at the P/Q-type VGCC.
authors.affiliation: Institute for Molecular Bioscience, University of Queensland, St Lucia, Australia.
authors.forename: Christina I
authors.initials: CI
authors.lastname: Schroeder
authors.forename: Mark L
authors.initials: ML
authors.lastname: Smythe
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Lewis
mesh_terms: D000818:Animals; D001671:Biochemistry / Q000379:methods; D002121:Calcium Channel Blockers / Q000737:chemistry / Q000494:pharmacology*; D020864:Calcium Channels, N-Type / Q000378:metabolism*; D015195:Drug Design; D004353:Drug Evaluation, Preclinical / Q000379:methods; D015640:Ion Channel Gating; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D018716:Molecular Mimicry; D010456:Peptides, Cyclic / Q000737:chemistry / Q000494:pharmacology*; D011487:Protein Conformation; D051381:Rats; D013329:Structure-Activity Relationship; D014688:Venoms / Q000737:chemistry / Q000378:metabolism*; D020960:omega-Conotoxins / Q000737:chemistry / Q000378:metabolism*
chemical_list: C461486:AM336; D002121:Calcium Channel Blockers; D020864:Calcium Channels, N-Type; D010456:Peptides, Cyclic; D014688:Venoms; D020960:omega-Conotoxins; C078452:ziconotide