title: Effect of point mutations on the secondary structure and membrane interaction of antimicrobial peptide anoplin.
abstract: Anoplin (GLLKRIKTLL-NH(2)) is the smallest linear α-helical antimicrobial peptide found naturally to date. Antibacterial and hemolytic properties of anoplin depend strongly on physicochemical properties. Two anoplin derivatives, anoplin-8K (Ano8K, GLLKTIKKLL-NH(2)) and anoplin-1K5 V8K (Ano1K5 V8K, KLLKVIKLL-NH(2)), were found to have increased bacterial and low hemolytic activity. In the present work physicochemical properties of these three peptides were studied by UV resonance Raman (UVRR) spectroscopy, Langmuir-Blodgett monolayer technique, and carboxyfluorescein (CF) leakage assay. UVRR data indicated that all three peptides adopt predominantly unordered conformation in aqueous buffer solution. In membrane-mimicking trifluoroethanol, the α-helical content increases for all three peptides with Ano1K5 V8K having the highest α-helix percentage, followed by Ano8K and anoplin. Critical micelle concentrations were found to be similar for all three peptides, and the saturation pressure decreases in the sequence Ano1K5 V8K, anoplin, Ano8K. Critical pressure of insertion was found to be greater for anionic lipid monolayer DPPG than for zwitterionic lipid DPPC indicating preferential adsorption of all three peptides to DPPG. Finally, membrane lytic activities of all three peptides toward various model lipid vesicles were compared through CF leakage assay. Overall the data indicate that antimicrobial activity of anoplin increases with charge, whereas membrane lytic activity correlates with peptides helicity and amphipathicity.
authors.affiliation: Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada.
authors.forename: Amy
authors.initials: A
authors.lastname: Won
authors.forename: Stahs
authors.initials: S
authors.lastname: Pripotnev
authors.forename: Annamaria
authors.initials: A
authors.lastname: Ruscito
authors.forename: Anatoli
authors.initials: A
authors.lastname: Ianoul
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism*; D004926:Escherichia coli / Q000166:cytology / Q000187:drug effects; D017354:Point Mutation; D017433:Protein Structure, Secondary; D013211:Staphylococcus aureus / Q000166:cytology / Q000187:drug effects; D013499:Surface Properties; D014862:Wasp Venoms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology*
chemical_list: D023181:Antimicrobial Cationic Peptides; D014862:Wasp Venoms; C443041:anoplin