Dissolved organic matter in water of Daugava river

Efficiency of energy transfer,%Efficiency of energy transfer,%Interaction of Fibrillar Insulin and Globin with Liposomes: ResonanceEnergy Transfer StudyM.Romanova *1 , I.Maliyov 1 , A.Kastorna 1 , K.Vus 1 , V.Trusova 1 , J.Molotkovsky 2 , G.Gorbenko 11 V.N. Karazin Kharkov National University, Kharkov, Ukraine;2 Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russiae-mail: romanova-mari@mail.ruA wide range of proteins are capable of assembling into cross β-sheet structures (amyloidfibrils) under pathological or nonphysiological conditions. The toxicity of amyloid fibrilsand their precursors is supposed to be associated with their action on structural andfunctional state of biological membranes. One way of approaching this problem is basedon the use of model systems consisting of lipid vesicles and protein aggregates formed invitro.The present study was directed towards clarifying the molecular details of interactionbetween globin or insulin fibrils and liposomes of different composition. Fibrillaraggregates were obtained by protein incubation in glycine buffer (pH 2.2) at 60 o C during8 days. To assess the extent of fibril binding to liposomes, we measured energy transferefficiency from tryptophan residues of globin or insulin to anthrylvinyl (AV) fluorophorecovalently attached to phosphatidylcholine (PC). Lipid vesicles were prepared from PCand its mixtures with anionic lipid phosphatidylserine (PS) (10, 20, 40 mol% PS).Increasing the concentration of globin fibrils resulted in the raise of AV fluorescenceintensity for all model systems under study (Fig.1). It was found that the most effectiveenergy transfer occurs when globin interacts with neutral PC vesicles. In the case ofinsulin, conversely, the energy transfer from Trp to AV-PC was negligible. Thisobservation can be explained by the fact that insulin has negative charge under theemployed experimental conditions (pH 7.4), which prevents protein binding to negativelycharged PC/PS liposomes.4.03.5PCPS10PS20PS404,03,53.03,02.52,52.02,01.51.00.50.00 2 4 6 8 10 12Concentration of Globin, M1,51,00,50,0InsulinGlobinFig.1. Efficiency of energy transfer as afunction of fibrillar globin concentrationFig.2. Comparison of energy transfer fromTrp to AV-PC for insulin and globinFig.2 illustrates the difference between fibrillar insulin and globin in the energy transferefficiency from Trp to AV-PC in PC bilayers. The results obtained allowed us to supposethat the character of interaction between globin fibrils and liposomes is mostlyhydrophobic, while in the case of insulin the role of electrostatics may be predominant.This work was supported by the grant from Fundamental Research State Fund of Ukraine(project number F.41.4/014).- 30 -