Fluorescence quenching in model membranes: phospholipid acyl chain distributions around small fluorophores

摘要: Fluorescence quenching in lipid bilayers is treated by a new approach based on calculation of the probability distribution and nonquenching acyl chains around fluorophore. The effect lattice site dependence (i.e., correlations phospholipid sister chain occupancy neighbor sites) was modeled use Monte Carlo simulations occupancy. This explicit accounting correlation found to fit observed behavior better than did model wherein quenchers are considered be independent. A key aspect this evaluate rate for bilayer composed pure lipid. In order rate, also provide strong test calculated distributions, we synthesized lipids with both labeled moiety (Br or nitroxide), as well more usual single-chain quenchers. fluorescence tryptophan octyl ester (TOE), 1,6-diphenyl-1,3,5-hexatriene (DPH) derivatives trimethylammonium-DPH (TMA-DPH) 1-lauroyl-2-(DPH-propionyl)phosphatidylcholine (DPH-PC), examined. We obtained consistent results all fluorophores indicating that up 18 neighboring sites can contribute quenching, corresponding two shells hexagonal lattice. Calculated discrete distributions intensities were converted into lifetimes compared Gaussian Lorentzian continuous lifetime distributions. theory presented here may used explain quantitatively heterogeneity fluorophore environments multicomponent membranes.