Luís M. S. Loura

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The aggregation of delta 5,7,9(11),22-ergostatetraen-3 beta-ol (dehydroergosterol or DHE), a fluorescent analog of cholesterol, was studied by photophysical techniques. It was concluded that the aqueous dispersions of DHE consist of strongly fluorescent microcrystals, and no evidence for self-quenching in micellar-type aggregates was found. The organization(More)
Large unilamellar vesicles of dimyristoylphosphatidylcholine/cholesterol mixtures were studied using fluorescence techniques (steady-state fluorescence intensity and anisotropy, fluorescence lifetime, and fluorescence resonance energy transfer (FRET)). Three compositions (cholesterol mole fraction 0.15, 0.20, and 0.25) and two temperatures (30 and 40(More)
100-ns molecular dynamics simulations of fluid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers, both pure and containing 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) acyl-chain labeled fluorescent analogs (C6-NBD-PC and C12-NBD-PC), are described. These molecules are widely used as probes for lipid structure and dynamics. The results obtained here(More)
Resonance energy transfer between octadecyl rhodamine B (donor) and 1,1',3,3,3',3'-hexamethylindotricarbocyanine (acceptor) was studied in a model system of membranes (large unilamellar vesicles of dipalmitoylphosphatidylcholine), using both steady-state and time-resolved techniques. In the fluid phase (temperature = 50 degrees C) the decay law and the(More)
The ternary lipid system palmitoylsphingomyelin (PSM)/palmitoyloleoylphosphatidylcholine (POPC)/cholesterol is a model for lipid rafts. Previously the phase diagram for that mixture was obtained, establishing the composition and boundaries for lipid rafts. In the present work, this system is further studied in order to characterize the size of the rafts.(More)
We present a combined theoretical (molecular dynamics, MD) and experimental (differential scanning calorimetry, DSC) study of the effect of 7-nitrobenz-2-oxa-1,3-diazol-4-yl (NBD) acyl chain-labeled fluorescent phospholipid analogs (C6-NBD-PC and C12-NBD-PC) on 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers. DSC measurements reveal that <1 mol%(More)
T-1249 is a HIV fusion inhibitor peptide under clinical trials. Its interaction with biological membrane models (large unilamellar vesicles) was studied using fluorescence spectroscopy. A gp41 peptide that includes one of the hydrophobic terminals of T-1249 was also studied. Both peptides partition extensively to liquid-crystalline POPC(More)
Vesicles of phosphatidylcholine/cholesterol mixtures show a wide composition range with coexistence of two fluid phases, the 'liquid disordered' (cholesterol-poor) and 'liquid ordered' (cholesterol-rich) phases. These systems have been widely used as models of membranes exhibiting lateral heterogeneity (membrane domains). The distributions of two(More)
A non-ideal lipid binary mixture (dilauroylphosphatidylcholine/distearoylphosphatidylcholine), which exhibits gel/fluid phase coexistence for wide temperature and composition ranges, was studied using photophysical techniques, namely fluorescence anisotropy, lifetime and resonance energy transfer (FRET) measurements. The FRET donor,(More)
A group of proteins with cell membrane remodeling properties is also able to change dramatically the morphology of liposomes in vitro, frequently inducing tubulation. For a number of these proteins, the mechanism by which this effect is exerted has been proposed to be the embedding of amphipathic helices into the lipid bilayer. For proteins presenting BAR(More)