title: The effect of binding of spider-derived antimicrobial peptides, oxyopinins, on lipid membranes.
abstract: Oxyopinins (Oxki1 and Oxki2) are antimicrobial peptides isolated from the crude venom of the wolf spider Oxyopes kitabensis. The effect of oxyopinins on lipid bilayers was investigated using high-sensitivity titration calorimetry and (31)P solid-state NMR spectroscopy. High-sensitivity titration calorimetry experiments showed that the binding of oxyopinins was exothermic, and the binding enthalpies (DeltaH) to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) small unilamellar vesicles (SUVs) were -18.1 kcal/mol and -15.0 kcal/mol for Oxki1 and Oxki2, respectively, and peptide partition coefficient (K(p)) was found to be 3.9x10(3) M(-1). (31)P NMR spectra of 1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine (DEPE) membranes in the presence of oxyopinins indicated that they induced a positive curvature in lipid bilayers. The induced positive curvature was stronger in the presence of Oxki2 than in the presence of Oxki1. (31)P NMR spectra of phosphaditylcholine (PC) membranes in the presence of Oxki2 showed that Oxki2 produced micellization of membranes at low peptide concentrations, but unsaturated PC membranes or acidic phospholipids prevented micellization from occurring. Furthermore, (31)P NMR spectra using membrane lipids from E. coli suggested that Oxki1 was more disruptive to bacterial membranes than Oxki2. These results strongly correlate to the known biological activity of the oxyopinins.
authors.affiliation: Suntory Institute for Bioorganic Research, 1-1-1 Wakayamadai, Shimamoto-Cho, Mishima-Gun, Osaka 618-8503, Japan. nomura@sunbor.or.jp <nomura@sunbor.or.jp>
authors.forename: Kaoru
authors.initials: K
authors.lastname: Nomura
authors.forename: Gerardo
authors.initials: G
authors.lastname: Corzo
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000378:metabolism*; D002942:Circular Dichroism; D008051:Lipid Bilayers; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013112:Spiders / Q000378:metabolism*; D013816:Thermodynamics
chemical_list: D000890:Anti-Infective Agents; D008051:Lipid Bilayers; D010455:Peptides