title: Engineering stable peptide toxins by means of backbone cyclization: stabilization of the alpha-conotoxin MII.
abstract: Conotoxins (CTXs), with their exquisite specificity and potency, have recently created much excitement as drug leads. However, like most peptides, their beneficial activities may potentially be undermined by susceptibility to proteolysis in vivo. By cyclizing the alpha-CTX MII by using a range of linkers, we have engineered peptides that preserve their full activity but have greatly improved resistance to proteolytic degradation. The cyclic MII analogue containing a seven-residue linker joining the N and C termini was as active and selective as the native peptide for native and recombinant neuronal nicotinic acetylcholine receptor subtypes present in bovine chromaffin cells and expressed in Xenopus oocytes, respectively. Furthermore, its resistance to proteolysis against a specific protease and in human plasma was significantly improved. More generally, to our knowledge, this report is the first on the cyclization of disulfide-rich toxins. Cyclization strategies represent an approach for stabilizing bioactive peptides while keeping their full potencies and should boost applications of peptide-based drugs in human medicine.
authors.affiliation: Institute for Molecular Bioscience and School of Biomedical Sciences, University of Queensland, Brisbane QLD 4072, Australia.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Clark
authors.forename: Harald
authors.initials: H
authors.lastname: Fischer
authors.forename: Louise
authors.initials: L
authors.lastname: Dempster
authors.forename: Norelle L
authors.initials: NL
authors.lastname: Daly
authors.forename: K Johan
authors.initials: KJ
authors.lastname: Rosengren
authors.forename: Simon T
authors.initials: ST
authors.lastname: Nevin
authors.forename: Frederic A
authors.initials: FA
authors.lastname: Meunier
authors.forename: David J
authors.initials: DJ
authors.lastname: Adams
authors.forename: David J
authors.initials: DJ
authors.lastname: Craik
mesh_terms: D000818:Animals; D002417:Cattle; D019439:Chromaffin Cells / Q000187:drug effects; D020916:Conotoxins / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D009538:Nicotine / Q000037:antagonists & inhibitors; D018733:Nicotinic Antagonists / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D009865:Oocytes / Q000378:metabolism; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D011487:Protein Conformation; D015202:Protein Engineering; D011978:Receptors, Nicotinic / Q000187:drug effects; D014981:Xenopus
chemical_list: D020916:Conotoxins; D018733:Nicotinic Antagonists; D010456:Peptides, Cyclic; D011978:Receptors, Nicotinic; C098872:alpha-conotoxin MII; D009538:Nicotine