title: Chemical Synthesis and Characterization of an Equinatoxin II(1-85) Analogue.
abstract: The chemical synthesis of an 85 residue analogue of the pore-forming protein, Equinatoxin II (EqtII), was achieved. Peptide precursors with over 40 residues were assembled by solid phase synthesis. The EqtII(1-46) fragment was modified to the reactive C-terminal thioester and native chemical ligation was performed with the A47C mutated EqtII(47-85) peptide to form the EqtII(1-85) analogue. Circular dichroism spectroscopy indicated that the N-terminal domain of EqtII(1-46) and EqtII(1-85) maintains predominantly an α-helical structure in solution and also in the presence of lipid micelles. This demonstrates the feasibility of assembling the full 179 residue protein EqtII via chemical means. Site-specific isotopic labels could be incorporated for structural studies in membranes by solid-state NMR spectroscopy.
authors.affiliation: School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia. jkaras@unimelb.edu.au.
authors.forename: John A
authors.initials: JA
authors.lastname: Karas
authors.affiliation: School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia. msani@unimelb.edu.au.
authors.forename: Marc-Antoine
authors.initials: MA
authors.lastname: Sani
authors.affiliation: School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, VIC 3010, Australia. fs@unimelb.edu.au.
authors.forename: Frances
authors.initials: F
authors.lastname: Separovic
mesh_terms: D002942:Circular Dichroism; D003064:Cnidarian Venoms / Q000138:chemical synthesis* / Q000737:chemistry; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008958:Models, Molecular; D017433:Protein Structure, Secondary
chemical_list: D003064:Cnidarian Venoms; D008055:Lipids; D008823:Micelles; C012307:equinatoxin
keywords: membrane protein structure; native chemical ligation; selectively labelled proteins; solid-phase peptide synthesis; solid-state NMR