title: Examining protein-lipid interactions in model systems with a new squarylium fluorescent dye.
abstract: The applicability of newly synthesized squarylium dye Sq to probing the changes in physical characteristics of lipid bilayer on the formation of protein-lipid complexes has been evaluated. Lipid vesicles composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with positively charged detergent cetyltrimethylammonium bromide (CTAB), anionic phospholipid cardiolipin (CL), and cholesterol (Chol) were employed as lipid component of model membrane systems while protein constituent was represented by lysozyme (Lz). Fluorescence intensity of Sq was found to decrease on Lz association with lipid bilayer. This effect was observed in all kinds of model systems suggesting that Sq is sensitive to modification of lipid bilayer physical properties on hydrophobic protein-lipid interactions. It was found that Sq spectral response to variations in Chol content depends on relative contributions of electrostatic and hydrophobic components of Lz-membrane binding.
authors.affiliation: Department of Biological and Medical Physics, V.N. Karazin Kharkov National University, 4 Svobody Sq., Kharkov 61077, Ukraine. vioffe@yandex.ru
authors.forename: Valeriya M
authors.initials: VM
authors.lastname: Ioffe
authors.forename: Galyna P
authors.initials: GP
authors.lastname: Gorbenko
authors.forename: Anatoliy L
authors.initials: AL
authors.lastname: Tatarets
authors.forename: Leonid D
authors.initials: LD
authors.lastname: Patsenker
authors.forename: Ewald A
authors.initials: EA
authors.lastname: Terpechnig
mesh_terms: D002308:Cardiolipins / Q000737:chemistry; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry; D002784:Cholesterol / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D050356:Lipid Metabolism; D008081:Liposomes / Q000737:chemistry / Q000378:metabolism; D008563:Membrane Lipids / Q000737:chemistry; D008954:Models, Biological; D015394:Molecular Structure; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism; D010713:Phosphatidylcholines / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry / Q000378:metabolism*; D013050:Spectrometry, Fluorescence
chemical_list: D002308:Cardiolipins; D002593:Cetrimonium Compounds; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D008081:Liposomes; D008563:Membrane Lipids; D010713:Phosphatidylcholines; D010743:Phospholipids; D011506:Proteins; D002784:Cholesterol; D009113:Muramidase; D000077286:Cetrimonium