Wyniki wyszukiwania - Biblioteka Nauki

1

Bariera hydrofobowa blon lipidowych. Wplyw cholesterolu i nienasyconych lancuchow alkilowych lipidow na transport czasteczek polarnych

100%

Wisniewska A. , Subczynski W. K.

Postępy Biologii Komórki. Suplement

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1995

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nr 05

59-72

2

Transport elektronów a zmiany płynności błon tylakoidów w czasie transformacji etioplastów w chloroplasty

100%

Subczynski W. K. , Machowicz E.

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nr 271

3

Three-dimensional dynamic structure of the lipid bilayer membranes: An EPR spin label study

100%

Subczynski W. K. , Wisniewska A.

Cellular and Molecular Biology Letters

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1996

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tom 01

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nr 4

EN

Over the last decade we have investigated the effects of cholesterol, polar carotenoids, and integral proteins (peptides) on the structure, dynamics, and hydrophobicity of saturated and unsaturated phosphatidylcholine (PC) membranes. The major results obtained in our studies can be summarized as follows: (1) The effect of unsaturation on the membrane alkyl chain order and reorientational motion is negligibly small; (2) The translational diffusion of lipids (lateral or vertical) as well as the diffusion of lipid-soluble small molecules is significantly decreased in cis- and trans-unsaturated PC membranes; (3) cis-unsaturated alkyl chains greatly decrease the ordering effect of membrane modifiers (cholesterol, polar carotenoids) as well as their effect on alkyl chain reorientational motion; (4) Introduction of a double bond into the alkyl chain increases the hydrophobicity (decreases water penetration) at all locations in the membrane; (5) Incorporation of cholesterol (30 mol%) decreases hydrophobicity (increases water penetration) from the polar headgroup region to a depth of approximately C7 and C9 for saturated and unsaturated PC membranes, respectively. Membrane hydrophobicity sharply increases at these positions from the level of methanol to the level of pure hexane, and hydrophobicity is constant in the inner region of the membrane.

4

Physical properties of lipid bilayer membranes: relevance to membrane biological functions

100%

Subczynski W. K. , Wisniewska A.

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2000

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tom 47

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nr 3

EN

Over the last 25 years one of us (WKS) has been investigating physical properties of lipid bilayer membranes. In 1991 a group led by WKS was organized into the Laboratory of Structure and Dynamics of Biological Membranes, the effective member of which is AW. Using mainly the electron paramagnetic resonance (EPR) spin-labeling method, we obtained unexpected results, which are significant for the better understanding of the functioning of biological membranes. We have developed a new pulse EPR spin-labeling method for the detection of membrane domains and evaluation of lipid exchange rates. This review will be focused on our main results which can be summarized as follows: (1) Unsaturation of alkyl chains greatly reduces the ordering and rigidifying effects of cholesterol although the unsaturation alone gives only minor fluidizing effects, as observed by order and reorientational motion, and rather significant rigidifying effects, as observed by translational motion of probe molecules; (2) Fluid-phase model membranes and cell plasma membranes are not barriers to oxygen and nitric oxide transport; (3) Polar carotenoids can regulate membrane fluidity in a way similar to cholesterol; (4) Formation of effective hydrophobic barriers to the permeation of small polar molecules across membranes requires alkyl chain unsaturation and/or the presence of cholesterol; (5) Fluid-phase micro-immiscibility takes place in cis-unsaturated phosphatidylcholine-cholesterol membranes and induces the formation of cholesterol-rich domains; (6) In membranes containing high concentrations of transmembrane proteins a new lipid domain is formed, with lipids trapped within aggregates of proteins, in which the lipid dynamics is diminished to the level of gel-phase.

5

Carotenoid-membrane interactions in liposomes: effect of dipolar, monopolar, and nonpolar carotenoids

80%

Wisniewska A. , Widomska J. , Subczynski W. K.

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2006

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tom 53

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nr 3

6

Profile polarności w poprzek błon fosfatydylocholinowych na granicy lipidów i gramicydy

80%

Wisniewska A. , Hyde J. S. , Kusumi A. , Subczynski W. K.

Current Topics in Biophysics. Supplement

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1992

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tom 16

7

The cis-carotenoid-membrane interactions

80%

Widomska J. , Subczynski W. K. , Gruszecki W. I. , Strzalka K.

Acta Biologica Cracoviensia. Series Botanica. Supplement

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2011

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tom 53

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nr 1

8

New mechanism in the protective action of carotenoids in membranes

80%

Markowska E. , Sielewiesiuk J. , Subczynski W. K.

Biophysics of Membrane Transport

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1990

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tom 10

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nr 2

9

Wpływ znaczników spinowych - nitroksylowych pochodnych kwasu stearynowego na główne przejście fazowe błony dimirystoilofosfatylocholinowej

80%

Wisniewska A. , Nishimoto Y. , Kusumi A. , Subczynski W. K.

Current Topics in Biophysics. Supplement

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1992

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tom 16

10

Structural aspects of the antioxidant activity of lutein in a model of photoreceptor membranes

80%

Wisniewska-Becker A. , Nawrocki G. , Duda M. , Subczynski W. K.

Acta Biochimica Polonica

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2012

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tom 59

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nr 1

EN

Lateral organization of membranes made from binary mixtures of dimyristoylphosphatidylcholine (DMPC) or dipalmitoylphosphatidylcholine (DPPC) and macular xanthophylls (lutein or zeaxanthin) was investigated using the saturation-recovery (SR) EPR spin-labeling discrimination by oxygen transport (DOT) method in which the bimolecular collision rate of molecular oxygen with the nitroxide spin label is measured. This work was undertaken to examine whether or not lutein and zeaxanthin, macular xanthophylls that parallel cholesterol in its function as a regulator of both membrane fluidity and hydrophobicity, can parallel other structural functions of cholesterol, including formation of the liquid-ordered phase in membranes. The DOT method permits discrimination of different membrane phases when the collision rates (oxygen transport parameter) differ in these phases. Additionally, membrane phases can be characterized by the oxygen transport parameter in situ without the need for separation, which provides information about the dynamics of each phase. In gel-phase membranes, two coexisting phases were discriminated in the presence of macular xanthophylls - namely, the liquid-ordered-like and solid-ordered-like phases. However, in fluid-phase membranes, xanthophylls only induce the solitary liquid-ordered-like phase, while at similar concentrations, cholesterol induces coexisting liquid-ordered and liquid-disordered phases. No significant differences between the effects of lutein and zeaxanthin were found.

11

Structural aspects of antioxidant activity of lutein in models of photoreceptor membranes

80%

Wisniewska-Becker A. , Nawrocki G. , Duda M. , Subczynski W. K.

Acta Biologica Cracoviensia. Series Botanica. Supplement

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2011

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tom 53

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nr 1

12

Can macular xanthophylls replace cholesterol in formation of the liquid-ordered phase in lipid-bilayer membranes?

80%

Subczynski W. K. , Wisniewska-Becker A. , Widomska J.

Acta Biochimica Polonica

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2012

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tom 59

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nr 1

EN

Lateral organization of membranes made from binary mixtures of dimyristoylphosphatidylcholine (DMPC) or dipalmitoylphosphatidylcholine (DPPC) and macular xanthophylls (lutein or zeaxanthin) was investigated using the saturation-recovery (SR) EPR spin-labeling discrimination by oxygen transport (DOT) method in which the bimolecular collision rate of molecular oxygen with the nitroxide spin label is measured. This work was undertaken to examine whether or not lutein and zeaxanthin, macular xanthophylls that parallel cholesterol in its function as a regulator of both membrane fluidity and hydrophobicity, can parallel other structural functions of cholesterol, including formation of the liquid-ordered phase in membranes. The DOT method permits discrimination of different membrane phases when the collision rates (oxygen transport parameter) differ in these phases. Additionally, membrane phases can be characterized by the oxygen transport parameter in situ without the need for separation, which provides information about the dynamics of each phase. In gel-phase membranes, two coexisting phases were discriminated in the presence of macular xanthophylls - namely, the liquid-ordered-like and solid-ordered-like phases. However, in fluid-phase membranes, xanthophylls only induce the solitary liquid-ordered-like phase, while at similar concentrations, cholesterol induces coexisting liquid-ordered and liquid-disordered phases. No significant differences between the effects of lutein and zeaxanthin were found.

13

Mikroskopowa sonda tlenowa. Tlenometria ERP

80%

Ligeza A. , Wisniewska A. , Subczynski W. K.

Current Topics in Biophysics. Supplement

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1992

|

tom 16

14

Zorientowana krystalizacja metaloporfiryn: wplyw pola magnetycznego i blon lipidowych.

80%

Subczynski W. K. , Pasienkiewicz-Gierula M. , Antholine W. E.

Postępy Biologii Komórki. Suplement

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2001

|

tom 16

285-296

15

Partitioning and transport of spin labeled drugs in model membranes

80%

Wojas J. , Pezeshk A. , Pezeshk V. , Subczynski W. K.

Biophysics of Membrane Transport

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1990

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tom 10

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nr 2

16

Spin-label oximetry in dense cell suspensions: Problems in closed-and open-chamber methods

80%

Ligeza A. , Swartz H. M. , Subczynski W. K.

Current Topics in Biophysics

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1994

|

tom 18

|

nr 1

17

Reoxidation of the reduced nitroxide radical spin label tempone: involvement of oxygen and oxygen-derived active forms

80%

Wisniewska A. , Ligeza A. , Subczynski W. K.

|

1992

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tom 16

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nr 2

18

Is a fluid-mosaic model of biological membranes fully relevant? Studies on lipid organization in model and biological membranes

80%

Wisniewska A. , Draus J. , Subczynski W. K.

Cellular and Molecular Biology Letters

|

2003

|

tom 08

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nr 1

EN

The basic concept of the fluid-mosaic model of Singer and Nicolson, an essential point of which is that the membrane proteins are floating in a sea of excess lipid molecules organized in the lipid bilayer, may be misleading in understanding the movement of membrane components in biological membranes that show distinct domain structure. It seems that the lipid bilayer is an active factor in forming the membrane structure, and the lipid composition is responsible for the presence of domains in the membrane. The main role in the process of domain formation is played by cholesterol and sphingolipids. The results presented here show that in a binary mixture of cholesterol and unsaturated phospholipids, cholesterol is segregated out from the bulk unsaturated liquid-crystalline phase. This forms cholesterol-enriched domains or clustered cholesterol domains due to the lateral nonconformability between the rigid planar ring structure of cholesterol and the rigid bend of the unsaturated alkyl chain at double bond position. These cholesterol-enriched domains may be stabilized by the presence of saturated alkyl chains of sphingomyelin or glycosphingolipids, and also by specific proteins which selectively locate in these domains and stabilize them as a result of protein-protein interaction. Such lipid domains are called “rafts” and have been shown to be responsible both for signal transduction to and from the cell and for protein sorting. We also looked at whether polar carotenoids, compounds showing some similarities to cholesterol and affecting membrane properties in a similar way, would also promote domain formation and locate preferentially in one of the lipid phases. Our preliminary data show that in the presence of cholesterol, lutein (a polar carotenoid) may segregate out from saturated lipid regions (liquid-ordered phase) and accumulate in the regions rich in unsaturated phospholipids forming carotenoid-rich domains there. Conventional and pulse EPR (electron paramagnetic resonance) spin labeling techniques were employed to assess the molecular organization and dynamics of the raft-constituent molecules and of the raft itself in the membrane.

19

Is the fluid-mosaic model of biological membranes fully relevant? Studies on lipid organization in model membranes

80%

Wisniewska A. , Draus J. , Subczynski W. K.

Cellular and Molecular Biology Letters

|

2002

|

tom 07

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nr Suppl.