title: Effective lipid-detergent system for study of membrane active peptides in fluid liposomes.
abstract: The structure of peptide antibiotic gramicidin A (gA) was studied in phosphatidylcholin liposomes modified by nonionic detergent Triton X-100. First, the detergent : lipid ratio at which the saturation of lipid membrane by Triton X-100 occurs (Re (sat)), was determined by light scattering. Measurements of steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene at sublytic concentrations of detergent showed that after saturation of the membrane by Triton X-100 microviscosity of lipid bilayer is reduced by 20%. The equilibrium conformational state of gA in phosphatidylcholine liposomes at Re (sat) was studied by CD spectroscopy. It was found that the conformational state of this channel-forming peptide changed crucially when Triton X-100 induced transition to more fluid membranes. The gA single-channel measurements were made with Triton X-100 containing bilayers. Tentative assignment of the channel type and gA structures was made by correlation of CD data with conductance histograms. Lipid-detergent system with variable viscosity developed in this work can be used to study the structure and folding of other membrane-active peptides.
authors.affiliation: Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, str, Moscow, Russia.
authors.forename: Sergei V
authors.initials: SV
authors.lastname: Sychev
authors.affiliation: Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, str, Moscow, Russia.
authors.forename: Stanislav V
authors.initials: SV
authors.lastname: Sukhanov
authors.affiliation: Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, str, Moscow, Russia.
authors.forename: Irina N
authors.initials: IN
authors.lastname: Telezhinskaya
authors.affiliation: Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya, str, Moscow, Russia.
authors.forename: Tatiana V
authors.initials: TV
authors.lastname: Ovchinnikova
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry; D003902:Detergents / Q000737:chemistry; D000067493:Dynamic Light Scattering; D006096:Gramicidin / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry*; D008560:Membrane Fluidity; D008564:Membrane Potentials; D017830:Octoxynol / Q000737:chemistry; D010713:Phosphatidylcholines / Q000737:chemistry*; D013025:Glycine max / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D003902:Detergents; D008081:Liposomes; D010713:Phosphatidylcholines; D006096:Gramicidin; D017830:Octoxynol; C017251:1,2-oleoylphosphatidylcholine; C028694:1-palmitoyl-2-oleoylphosphatidylcholine
keywords: CD spectroscopy; Fluorescence anisotropy; Membrane fluidity; Membrane-active peptide; gA conformation