In this paper, we present studies concerning phenyltin adsorption onto the dipalmitoylphosphatidylcholine bilayer. Phenyltin compounds are known to be biologically active, and their molecular geometry makes it possible to study the effect... more
In this paper, we present studies concerning phenyltin adsorption onto the dipalmitoylphosphatidylcholine bilayer. Phenyltin compounds are known to be biologically active, and their molecular geometry makes it possible to study the effect of steric constraints on their ability to penetrate the model lipid membrane. Using a fluorescence probe as a reporter of the amount of adsorbed compound, we evaluated their affinity to the membrane as a function of the membrane state. The amount of the adsorbed compound was found to depend on the adsorbing molecule's geometry and lipid bilayer organization. The fluorescence measurements were supported by the density functional theory (DFT) method of quantum mechanical computations. The penetrant location was correlated with the possible relative positions of its polar and hydrophobic moieties to determine if it could adopt structural requirements of the local membrane environment. Molecules were deformed by a model force, mimicking interactions within the membrane interfacial region. Computations show that the diphenyltin molecule can be deformed to such an extent that it can adopt an amphiphilic conformation. Triphenyltin is different, as its bending requires more energy. Born repulsion energies from hydrophobic fluid into water for phenyltins were also computed in an isodensity-polarized continua model of DFT computation. Our results indicate that the phenyltin compounds incorporate into the interface of the lipid membrane, although diphenyltin integrates more deeply than triphenyltin, which locates on the double layer's surface, and this is due to the fact that the main role is played by steric and not electrostatic interactions.
Research Interests: Microbiology, Chemistry, Medical Microbiology, Membrane Biology, Medicine, and 15 moreAdsorption, Lipid Membranes, Animals, Liposomes, Membrane, Chickens, Fluorescent probes, Molecular Conformation, Lipid bilayers, Biological activity, Molecule, Lipid Bilayer, Biochemistry and cell biology, Electrostatic interaction, and Egg yolk
... Marek Langner,; Janina Gabrielska,; Halina Kleszczyńska,; Hanna Pruchnik. Article first published online: 4 DEC 1998. DOI: 10.1002/(SICI)1099-0739(199802)12:2<99::AID-AOC674>3.0.CO;2-K. Copyright © 1998 John... more
... Marek Langner,; Janina Gabrielska,; Halina Kleszczyńska,; Hanna Pruchnik. Article first published online: 4 DEC 1998. DOI: 10.1002/(SICI)1099-0739(199802)12:2<99::AID-AOC674>3.0.CO;2-K. Copyright © 1998 John Wiley & Sons, Ltd. Issue. Applied Organometallic Chemistry ...
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Dietary fats have been shown by many investigators to affect immune responses in vitro and in vivo. However, the exact mechanism(s) by which fats or their metabolic derivatives affect immune function is still unknown. In this report we... more
Dietary fats have been shown by many investigators to affect immune responses in vitro and in vivo. However, the exact mechanism(s) by which fats or their metabolic derivatives affect immune function is still unknown. In this report we have investigated whether short-term in vitro exposure to fatty acids alters the adhesion of lymphocytes to extracellular matrix proteins. We found remarkably heterogeneous effects with these agents on lymphocyte adhesion; increases and decreases in adhesion were observed depending upon the fatty acid, cell type and extracellular matrix protein used. Alterations in the adhesion potential of lymphocytes could serve as a mechanism for the reported effects of fatty acids on immune function since lymphocytes are dependent upon rapid and reversible adherence events for most of their effector activities.
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Thermotropic properties of liposome membranes prepared of bulk bovine erythrocyte membrane lipids, native, or aldolase-modified, were investigated by the ESR method. Breaks were observed in the log 2T parallel vs 1/T plots for two spin... more
Thermotropic properties of liposome membranes prepared of bulk bovine erythrocyte membrane lipids, native, or aldolase-modified, were investigated by the ESR method. Breaks were observed in the log 2T parallel vs 1/T plots for two spin labels: tempopalmitate and 5-doxyl-palmitate methyl ester. These phenomena have been interpreted as reflecting structural changes near the lipid bilayer polar heads region. Upon modification with aldolase, the temperature at which the breaks occurred was decreased for both spin probes.
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Interaction between the plasma membrane and aggregate lipid surface determines how efficiently the encapsulated drug will be delivered into the cell. Electrostatic interactions are one of the main forces affecting liposome and aggregate... more
Interaction between the plasma membrane and aggregate lipid surface determines how efficiently the encapsulated drug will be delivered into the cell. Electrostatic interactions are one of the main forces affecting liposome and aggregate association with the charged cell surface. In this study, the effect of surface charge on the association of liposomes with human colon CX-1.1 cancer cells was studied. When phosphatidylserine was incorporated into a lipid bilayer, the amount of liposomes associated with cells tended to increase along with the amount of negatively charged lipid present in the liposomal lipid bilayer. When the cationic lipid dioleoyl-1,2-diacyl-3-trimethylammonium-propane (DOTAP) was included into the liposome formula, their uptake by the cells was also increased. Maximum binding occurred when the amount of positively charged lipids in liposomes was about 10 mol% of lipids.
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The antioxidative activity of three anthocyanin pigments, extracted from the fruits of chokeberry, honeysuckle and sloe, were studied. Lipid oxidation in the liposome membrane, induced by UV radiation, was evaluated with a thiobarbituric... more
The antioxidative activity of three anthocyanin pigments, extracted from the fruits of chokeberry, honeysuckle and sloe, were studied. Lipid oxidation in the liposome membrane, induced by UV radiation, was evaluated with a thiobarbituric acid-reactive substances assay. The antioxidant efficiency of the studied compounds follows this sequence: chokeberry > sloe > honeysuckle. The extract concentrations at which a 50% reduction of phosphatidylcho line oxidation was observed, were respectively: 48, 54 and 60 mg/1. The end products of lipid membrane oxidation were evaluated using HPLC. It was found that the antioxidative potency of anthocyanin extracts is concentration-dependent. As shown by E P R technique the efficiency of the extracts to eliminate free radicals from the solution follows the order of the antioxidant activity.
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Background: Fluorescence correlation spectroscopy (FCS) can be used for the determination of diffusion coefficients of single molecules. Since diffusion coefficients are correlated with size and shape of the labeled species, FCS provides... more
Background: Fluorescence correlation spectroscopy (FCS) can be used for the determination of diffusion coefficients of single molecules. Since diffusion coefficients are correlated with size and shape of the labeled species, FCS provides information on conformational changes in plasmids aggregates. Methods: A 10-kbp plasmid stained with PicoGreen® was condensed by spermine or liposomes formulated from cationic lipid and egg phosphatidylcholine. Results: The diffusion coefficient of DNA increases from 1.0 × 10–12 m2/s to 3.2 × 10–12 m2/s by the addition of spermine, whereas the addition of cationic liposomes leads to complexes characterized by diffusion coefficients with values ranging from 1.7 to 1.9 × 10–12 m2/s. Conclusions: FCS experiments allow determining the diffusion coefficients of DNA-containing aggregates which provide information regarding the topology and homogeneity of the aggregate.
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Research Interests: Algorithms, Protein Folding, Biology, Cell Biology, Cell line, and 15 moreHumans, Sequence alignment, Ankyrin, Circular Dichroism, Escherichia coli, Mice, Animals, Liposomes, Membrane Lipids, HeLa cells, Red blood cell, Binding Site, Biochemistry and cell biology, Molecular Sequence Data, and binding sites
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Research Interests: Biophysics, Chemistry, Medicine, Biological Sciences, Elasticity, and 15 moreEscherichia coli, Animals, Cationic polymerization, Physical sciences, Light, Liposomes, Liposome, Plasmids, CHEMICAL SCIENCES, Laurdan, Quaternary Ammonium Compounds, Drug Carriers, Gene Transfer, CHO cells, and Cricetinae
Research Interests: Chemical Engineering, Chemistry, Chromatography, Phospholipids, Medicine, and 12 moreBiological Sciences, Physical sciences, Liposome, Phase Change, Vesicle, Lipid bilayers, Biological activity, Free Fatty Acid, Hydrogen-Ion Concentration, Lipid Bilayer, Phosphatidylcholine, and Biochemistry and cell biology
Research Interests: Chemical Engineering, Chemistry, Phospholipids, Medicine, Biological Sciences, and 15 moreBrain, Fatty acids, Cholesterol, Animals, Physical sciences, Spectrin, Membrane, Lipid Raft, Monolayer, Erythrocytes, Phosphatidylcholine, Phosphatidylserine, Chemical Structure, Membrane Fluidity, and Biochemistry and cell biology
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Water transport through spherical lipid bilayers consisting of bovine red cell lipids has been studied. A new experimental method for the determination of volume flow induced by concentration gradient is described. Changes of the... more
Water transport through spherical lipid bilayers consisting of bovine red cell lipids has been studied. A new experimental method for the determination of volume flow induced by concentration gradient is described. Changes of the filtration coefficient indicate phase transition in membrane lipid taking place at 33-36 degrees C.
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The analysis of time-dependent fluorescence shifts of the bilayer probe 6-hexadecanoyl-2-(((2-(trimethylammonium)ethyl)methyl)amino)naphthalene chloride (Patman) offers valuable information on the hydration and dynamics of phospholipid... more
The analysis of time-dependent fluorescence shifts of the bilayer probe 6-hexadecanoyl-2-(((2-(trimethylammonium)ethyl)methyl)amino)naphthalene chloride (Patman) offers valuable information on the hydration and dynamics of phospholipid headgroups. Quenching studies on vesicles composed of four phosphatidylcholines with different hydrocarbon chains (18:1c9/18:1c9, DOPC; 16:0/18:1c9, POPC; 18:1c9/16:0, OPPC; 18:1c6/18:1c6, PCDelta6) show that the chromophore of Patman is defined located at the level of the sn-1 ester-group in the phospholipid, which is invariant to the hydrocarbon chain. The so-called solvent relaxation (SR) approach as well as solid-state 2H NMR reveals that DOPC and PCDelta6 are more hydrated than POPC and OPPC. A strong dependence of SR kinetics on the position of double bond in the investigated fatty acid chains was observed. Apparently, the closer the double bond is located to the hydrated sn-1 ester-group, the more mobile this group becomes. This work demonstrates that the SR approach can report mobility changes within phospholipid bilayers with a remarkable molecular resolution.
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Fluorescein-PE is a fluorescence probe that is used as a membrane label or a sensor of surface associated processes. Fluorescein-PE fluorescence intensity depends not only on bulk pH, but also on the local electrostatic potential, which... more
Fluorescein-PE is a fluorescence probe that is used as a membrane label or a sensor of surface associated processes. Fluorescein-PE fluorescence intensity depends not only on bulk pH, but also on the local electrostatic potential, which affects the local membrane interface proton concentration. The pH sensitivity and hydrophilic character of the fluorescein moiety was used to detect conformational changes at the lipid bilayer surface. When located in the dipalmitoylphosphatidylcholine (DPPC) bilayer, probe fluorescence depends on conformational changes that occur during phase transitions. Relative fluorescence intensity changes more at pretransition than at the main phase transition temperature, indicating that interface conformation affects the condition in the vicinity of the membrane. Local electrostatic potential depends on surface charge density, the local dielectric constant, salt concentration and water organisation. Initial increase in fluorescence intensity at temperatures ...
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Spherocytosis is a hereditary disease. It results from mutations in genes that encode proteins participating in the attachment of the membrane skeleton to the plasma membrane bilayer of the erythrocyte. In affected cells, interaction... more
Spherocytosis is a hereditary disease. It results from mutations in genes that encode proteins participating in the attachment of the membrane skeleton to the plasma membrane bilayer of the erythrocyte. In affected cells, interaction between the spectrin-actin meshwork and integral membrane proteins is altered. This results in the weakening of plasma membrane mechanical resistance and diminishing its elasticity. Since defective