Wyniki wyszukiwania

1

The effect of the presence of crown ether on ion transport across the lipid bilayer

100%

Naumowicz M., Petelska A. D., Figaszewski Z. A.

Cellular and Molecular Biology Letters

|

2002

|

tom 07

|

nr Suppl.

2

Amphiphilic counterion effect on gell-fluid phase transition of lipid bilayers

80%

Kubica K.

Biophysics of Membrane Transport

|

1994

|

tom 12

|

nr 2

3

Peptides in lipid bilayers: structural and thermodynamic basis for partitioning and folding

80%

White S. H.

Biophysics of Membrane Transport

|

1994

|

tom 12

|

nr 2

4

Effect of ethanol on lipid bilayer relaxation kinetics

80%

Przybylo M., Borowik T., Kraszewski S., Langner M.

Cellular and Molecular Biology Letters

|

2005

|

tom 10

|

nr Suppl.

5

Computer studies of fluorescein-PE-interaction with the lipid bilayer

70%

Kubica K.

Cellular and Molecular Biology Letters

|

2002

|

tom 07

|

nr Suppl.

6

Exploring the effect of xenon on biomembranes

70%

Stimson L. M., Vattulainen I., Rog T., Karttunen M.

Cellular and Molecular Biology Letters

|

2005

|

tom 10

|

nr 4

7

Thioridazine induces erythrocyte stomatocytosis due to interactions with negatively charged lipids

61%

Hendrich A. B., Lichacz K., Burek A., Michalak K.

Cellular and Molecular Biology Letters

|

2002

|

tom 07

|

nr 4

Despite the fact that thioridazine is used clinically as a neuroleptic drug, little is known about the molecular mechanisms underlying its biological effects, in particular about its interactions with membranes. In the present work we investigate the influence of thioridazine on model and cell membranes, using calorimetry, DPH fluorescence polarization measurements, studies of haemolysis and scanning electron microscopy. The experiments show that thioridazine interacts with lipid bilayers and intercalates into bilayer structure. We found that erythrocyte stomatocytosis induced by the drug might be related to preferential interaction of thioridazine with charged lipids.

8

The liquid-ordered phase in sphingomyelin-cholesterol membranes as detected by the discrimination by oxygen transport [DOT] method

61%

Wisniewska A., Subczynski W. K.

Cellular and Molecular Biology Letters

|

2008

|

tom 13

|

nr 3

430-451

Membranes made from binary mixtures of egg sphingomyelin (ESM) and cholesterol were investigated using conventional and saturation-recovery EPR observations of the 5-doxylstearic acid spin label (5-SASL). The effects of cholesterol on membrane order and the oxygen transport parameter (bimolecular collision rate of molecular oxygen with the nitroxide spin label) were monitored at the depth of the fifth carbon in fluid- and gel-phase ESM membranes. The saturation-recovery EPR discrimination by oxygen transport (DOT) method allowed the discrimination of the liquid-ordered (l o), liquid-disordered (l d), and solid-ordered (s o) phases because the bimolecular collision rates of the molecular oxygen with the nitroxide spin label differ in these phases. Additionally, oxygen collision rates (the oxygen transport parameter) were obtained in coexisting phases without the need for their separation, which provides information about the internal dynamics of each phase. The addition of cholesterol causes a dramatic decrease in the oxygen transport parameter around the nitroxide moiety of 5-SASL in the l o phase, which at 50 mol% cholesterol becomes ∼5 times smaller than in the pure ESM membrane in the l d phase, and ∼2 times smaller than in the pure ESM membrane in the s o phase. The overall change in the oxygen transport parameter is as large as ∼20-fold. Conventional EPR spectra show that 5-SASL is maximally immobilized at the phase boundary between regions with coexisting l d and l o phases or s o and l o phases and the region with a single l o phase. The obtained results all owed for the construction of a phase diagram for the ESM-cholesterol membrane.

9

The dependence of fluorescein-PE fluorescence intensity on lipid bilayer state. Evaluating the interaction between the probe and lipid molecules

61%

Kubica K., Langner M., Gabrielska J.

Cellular and Molecular Biology Letters

|

2003

|

tom 08

|

nr 4

The degree of dependence of a lipid bilayer’s surface properties on its conformational state is still an unresolved question. Surface properties are functions of molecular organization in the complex interfacial region. In the past, they were frequently measured using fluorescence spectroscopy. Since a fluorescent probe provides information on its local environment, there is a need to estimate the effect caused by the probe itself. In this paper, we address this question by calculating how lipid head-group orientation effects the fluorescence intensity of Fluorescein-PE (a probe that is sensitive to surface potential). In the theoretical model assumed the lipid bilayer state and the interactions between the charged fluorescent probe and the surrounding lipid molecules was evaluated. The results of this theoretical analysis were compared with experimentally obtained data. A lipid bilayer formed from DPPC was chosen as the experimental system, since it exhibits all the major conformational states within a narrow temperature range of 30°C - 45°C. Fluorescein-PE fluorescence intensity depends on local pH, which in turn is sensitive to local electrostatic potential in the probe’s vicinity. This local electrostatic potential is generated by lipid head-group dipole orientation. We have shown that the effect of the probe on lipid bilayer properties is limited when the lipid bilayer is in the gel phase, whereas it is more pronounced when the membrane is liquid-crystalline. This implies that Fluorescein-PE is a good reporter of local electrostatic fields when the lipid bilayer is in the gel phase, and is a poor reporter when the membrane is in the liquid-crystalline state.

10

Influence of amphiphilic anionic and cationic mixture on calcium ion desorption from lipid membranes. I. Experiments with small unilamellar vesicles

61%

Fogt A., Kubica K., Kuczera J.

Polish Journal of Environmental Studies

|

1994

|

tom 03

|

nr 4

This paper studies the influence of equimolar mixtures of biologically-active cationic and anionic amphiphiles (dodecyl-oxymethylene-methyl-morpholinium chloride (DOMM) and one of the series of sodium alkylsulphonates (ASJ with n = 1,2,4,6,8,10,12 and 14 carbon atoms in the alkyl chain) on calcium ion desorption from lecithin liposome membranes. It was shown that by choosing the hydrophobic part of the amphiphilic anion in the mixture one can regulate the efficiency of the amphiphilic cation towards the desorption process. The rate constant of that process strongly depends on the surfactant concentration. The differences in the effectiveness of the different compounds are most distinct at lower concentrations and vanish when the concentration increases. The results are discussed in response to the amphiphilic ion-pair hydrophobicity and their electrical properties. The role of the hypothetical, temporal complexes consisting of the alkylsulphonate anion(s) and calcium cation (ASn-Ca)+ in the calcium ion exchange is discussed. The mechanism of Ca2+ desorption from the surface of the phospholipid bilayer under the simultaneous action of the cationic and anionic detergents is proposed. According to our proposal calcium ion release occurs due to the joint action of the monovalent cationic and anionic detergents in coincidence with a divalent calcium ion. To authenticate the proposed mechanisms of calcium ion release, the shapes of the experimental curves were compared with the theoretical ones obtained by computer simulation using the cellular automata method.

11

The effect of lipid bilayer organization on the adsorption of organometallic, amphiphilic molecules

61%

Langner M., Gabrielska J., Przestalski S.

Cellular and Molecular Biology Letters

|

1999

|

tom 04

|

nr 2

12

Properties of lipid bilayers modified by long-chain polyprenols

61%

Walinska K., Janas T., Chojnacki T., Swiezewska E., Janas T.

Cellular and Molecular Biology Letters

|

1997

|

tom 02

|

nr 1

13

The interaction of thioridazine with model lipid bilayers and erythrocyte membranes

61%

Hendrich A. B., Lichacz K., Burek A., Michalak K.

Cellular and Molecular Biology Letters

|

2002

|

tom 07

|

nr Suppl.

14

The appearance of multistates pores due to the lipid bilayers selfoscillations

61%

Bota M., Popescu D.

Biophysics of Membrane Transport

|

1994

|

tom 12

|

nr 2

15

The association of glycolytic enzymes with cellular and model membranes

61%

Gutowicz J., Terlecki G.

Cellular and Molecular Biology Letters

|

2003

|

tom 08

|

nr 3

This article deals with the binding of glycolytic enzymes with membranous or protein subcellular structures. The representative papers of the last three decades dealing with this matter are reviewed. The studies evidencing the binding of some glycolytic enzymes to insoluble subcellular proteins and membranous structures are presented. It is currently generally accepted that the glycolytic enzymes work in some organisation. Such organisation undoubtedly plays a marked role, although still poorly known, in the regulation processes of glycolysis. From this review, the conclusion emerges that the regulatory ability of the binding of glycolytic enzymes to cellular membranes should be added to the list of well-known mechanisms of post-translational regulation of the glycolytic enzymes. Some of the results presented are the background for the hypothesis that planar phospholipid domains in/on the membrane surface are capable of functioning as binding sites for these enzymes. Such binding can modify the conformation state of the enzymes, which results in changes in their kinetic properties; thus, it may function as a regulator of catalytic activity.

16

Perturbation of the lipid phase of a membrane is not involved in the modulation of MRP1 transport activity by flavonoids

51%

Wesolowska O., Hendrich A. B., Lania-Pietrzak B., Wisniewski J., Molnar J., Ocsovszki I., Michalak K.

Cellular and Molecular Biology Letters

|

2009

|

tom 14

|

nr 2

199-221

The expression of transmembrane transporter multidrug resistance-associated protein 1 (MRP1) confers the multidrug-resistant phenotype (MDR) on cancer cells. Since the activity of the other MDR transporter, P-glycoprotein, is sensitive to membrane perturbation, we aimed to check whether the changes in lipid bilayer properties induced by flavones (apigenin, acacetin) and flavonols (morin, myricetin) were related to their MRP1 inhibitory activity. All the flavonoids inhibited the efflux of MRP1 fluorescent substrate from human erythrocytes and breast cancer cells. Morin was also found to stimulate the ATPase activity of erythrocyte ghosts. All flavonoids intercalated into phosphatidylcholine bilayers as judged by differential scanning calorimetry and fluorescence spectroscopy with the use of two carbocyanine dyes. The model of an intramembrane localization for flavones and flavonols was proposed. No clear relationship was found between the membrane-perturbing activity of flavonoids and their potency to inhibit MRP1. We concluded that mechanisms other than perturbation of the lipid phase of membranes were responsible for inhibition of MRP1 by the flavonoids.

17

Transmembrane segment M2 of glycine receptor as a model system for the pore-forming structure of ion channels

51%

Bednarczyk P., Szewczyk A., Dolowy K.

Acta Biochimica Polonica

|

2002

|

tom 49

|

nr 4

The glycine receptor belongs to the ligand-gated ion channel superfamily. It is a chloride conducting channel composed of four transmembrane domains. It was previously shown that the second transmembrane domain (M2) of the glycine receptor forms an ion conduction pathway throught lipid bilayers. The amino-acid sequence of the transmembrane segment M2 of the glycine receptor has a high homology to all receptors of the ligand-gated ion channel superfamily. In our report, we have used a synthetic M2 peptide. It was incorporated into a planar membrane of known lipid composition and currents induced by M2 were measured by the Black Lipid Membrane technique. When the planar lipid bilayer was composed of 75% phosphatidylethanolamine and 25% phosphatidylserine, the reversal potential measured in a 150/600 mM KCl (cis/trans) gradient was -19 mV suggesting that the examined pore was preferential to anions, Pk/Pci = 0.25. In contrast, when 75% phosphatidylserine and 25% phosphatidylethanolamine was used, the reversal potential was +20 mV and the pore was preferential to cations, Pk/Pci = 4.36. Single-channel currents were recorded with two predominant amplitudes corresponding to the main-conductance and sub-conductance states. Both conductance states (about 12 pS and 30 pS) were measured in a symmetric solution of 50 mM KCl. The observed single-channel properties suggest that the selectivity and conductance of the pore formed by the M2 peptide of the glycine receptor depend on the lipid composition of the planar bilayer.

18

The mystery of phospholipid flip-flop in biogenic membranes

51%

Gummadi S. N., Kumar K. S.

Cellular and Molecular Biology Letters

|

2005

|

tom 10

|

nr 1

19

Construction and optimisation of a computer model for a bacterial membrane

51%

Murzyn K., Pasenkiewicz-Gierula M.

Acta Biochimica Polonica

|

1999

|

tom 46

|

nr 3

The main steps in the construction of a computer model for a bacterial membrane are described. The membrane has been built of 72 lipid molecules, 54 of which being 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphatidylethanolamine (POPE) and 18 - 1-palmitoyl-2-oleoyl-sn-glycerol-3-phosphatidyl-rac-glycerol (POPG) molecules (thus in the proportion of 3:1). The membrane was hydrated with 1955 water molecules (approximately 27 water molecules per lipid). To neutralise the electronic charge (-e) on each POPG molecule, 18 sodium ions (Na+) were added to the membrane close to the POPG phosphate groups. The atomic charges on the POPE and POPG headgroups were obtained from ab initio quantum mechanical restrained electrostatic potential fitting (RESP) (Bayly et al., 1993, J. Phys. Chem. 97, 10269) using the GAMESS program at the 6-31G* level (Schmidt et al., 1993, J. Comput. Chem. 14, 1347). The model constructed in this way provided an initial structure for subsequent molecular dynamics simulation studies intended to elucidate the atomic level interactions responsible for the structure and dynamics of the bacterial membrane.

20

The role of mitotic vesicles in the nuclear assembly

51%

Rzepecki R., Smythe C., Hutchison C. J.

Cellular and Molecular Biology Letters

|

2002

|

tom 07

|

nr 2

Ograniczanie wyników

The effect of the presence of crown ether on ion transport across the lipid bilayer

Amphiphilic counterion effect on gell-fluid phase transition of lipid bilayers

Peptides in lipid bilayers: structural and thermodynamic basis for partitioning and folding

Effect of ethanol on lipid bilayer relaxation kinetics

Computer studies of fluorescein-PE-interaction with the lipid bilayer

Exploring the effect of xenon on biomembranes

Thioridazine induces erythrocyte stomatocytosis due to interactions with negatively charged lipids

The liquid-ordered phase in sphingomyelin-cholesterol membranes as detected by the discrimination by oxygen transport [DOT] method

The dependence of fluorescein-PE fluorescence intensity on lipid bilayer state. Evaluating the interaction between the probe and lipid molecules

Influence of amphiphilic anionic and cationic mixture on calcium ion desorption from lipid membranes. I. Experiments with small unilamellar vesicles

The effect of lipid bilayer organization on the adsorption of organometallic, amphiphilic molecules

Properties of lipid bilayers modified by long-chain polyprenols

The interaction of thioridazine with model lipid bilayers and erythrocyte membranes

The appearance of multistates pores due to the lipid bilayers selfoscillations

The association of glycolytic enzymes with cellular and model membranes

Perturbation of the lipid phase of a membrane is not involved in the modulation of MRP1 transport activity by flavonoids

Transmembrane segment M2 of glycine receptor as a model system for the pore-forming structure of ion channels

The mystery of phospholipid flip-flop in biogenic membranes

Construction and optimisation of a computer model for a bacterial membrane

The role of mitotic vesicles in the nuclear assembly