Wyniki wyszukiwania

1

Red blood cell shape and deformability in the context of the functional evolution of its membrane structure

100%

Svetina S.

Cellular and Molecular Biology Letters

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2012

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tom 17

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nr 2

It is proposed that it is possible to identify some of the problems that had to be solved in the course of evolution for the red blood cell (RBC) to achieve its present day effectiveness, by studying the behavior of systems featuring different, partial characteristics of its membrane. The appropriateness of the RBC volume to membrane area ratio for its circulation in the blood is interpreted on the basis of an analysis of the shape behavior of phospholipid vesicles. The role of the membrane skeleton is associated with preventing an RBC from transforming into a budded shape, which could form in its absence due to curvature-dependent transmembrane protein-membrane interaction. It is shown that, by causing the formation of echinocytes, the skeleton also acts protectively when, in vesicles with a bilayer membrane, the budded shapes would form due to increasing difference between the areas of their outer and inner layers.

2

The carbamylation of proteins leads to alterations in the membrane structure of erythrocytes

100%

Pieniazek A., Gwozdzinski K.

Cellular and Molecular Biology Letters

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2002

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tom 07

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nr Suppl.

3

Carbamylation of proteins leads to alterations in the membrane structure of erythrocytes

84%

Pieniazek A., Gwozdzinski K.

Cellular and Molecular Biology Letters

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2003

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tom 08

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nr 1

The effect of the sodium cyanate-induced carbamylation (carbamoylation) of proteins in erythrocytes was studied using spin labelling and spectrophotometric methods. The experiments were conducted in whole blood and in erythrocytes in phosphate buffer using 25 mmol/L of sodium cyanate. Lipid membrane fluidity was determined using three spin-labelled fatty acids: 5-, 12- and 16-doxylstearic acids (5-DS, 12-DS, 16-DS). Internal viscosity was measured with Tempamine, using also EPR spectroscopy. Osmotic fragility was determined spectrophotometrically. Incubation of whole blood with sodium cyanate led to an increase in lipid membrane fluidity in the deeper region of the lipid layer, indicated by 12- and 16-doxylstearic acid, and a decrease near the surface (5-DS). Statistically significant results were obtained for the internal viscosity and osmotic fragility of erythrocytes. An increase in internal viscosity and increase in osmotic fragility were found in erythrocytes after incubation of whole blood, as well as in erythrocytes incubated with sodium cyanate in buffer. Alterations in internal viscosity were stronger in erythrocytes incubated with sodium cyanate in blood than in erythrocytes in the buffer. On the other hand, higher osmotic fragility was observed for erythrocytes in the buffer.

4

Molecular mechanisms of interaction between amphiphilic ammonium salts and membranes

84%

Przestalski S., Kuczera J.

Polish Journal of Environmental Studies

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1992

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tom 01

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nr 2

This paper is a review of studies on the interaction between cationic, amphiphilic quaternary ammonium salts and biological and model membranes. It has been pointed out that the compounds studied induce changes in both passive and active membrane properties such as mechanical, transport liquid-crystalline and electrical . An attempt has been made to explain the observed effects on the basis of the molecular shape and hydrophobic matching concepts. Some practical implications of the observations and their interpretation have also been noted.

5

Biophysical properties that control size and shape of extruded liposomes

84%

Gawrisch K., Jin A. J., Huster D., Holte L. L., Koenig B.

Cellular and Molecular Biology Letters

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1999

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tom 04

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nr 2

6

Conformations, orientations and time scales characterising dimyristoylphosphatidylcholine bilayer membrane. Molecular dynamics simulation studies

84%

Pasenkiewicz-Gierula M., Rog T.

Acta Biochimica Polonica

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1997

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tom 44

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nr 3

The results of molecular dynamics simulation of fully hydrated dimyristoylphosphatidylcholine (DMPC) bilayer membrane in the liquid-crystalline phase are presented. They show that the probability of a gauche conformation varies periodically along the chain with only a slight increase towards the end of the chain. However, the frequency of transition between conformations increases, due to a decrease in the lifetime of the trans conformation, along the chain. The average lifetimes for trans conformations are in the range of 1-2 x 10-10 s and for gauche conformations in the range of 4-7 x 10-11 s. The α-chain of the DMPC head group has mainly an extended conformation, due to predominantly trans conformation of α5 torsion. The rotational correlation time for the P-N vector is 3.7 ns. The C2-C1-011-P fragment of the DMPC head group (θ1, α1, α2 torsions) is rigid while the P-012-C11-C12 fragment ( α3, α4, α5 torsions) is flexible. The lateral diffusion coefficient for DMPC self-diffusion in the membrane is 2 x 10-7 cm2/s; the rate of transverse diffusion is the same. Large differences in the calculated rotational correlation times for the a-, β-, γ-chains and for the 021-Cl-vector indicate that in the liquid-crystalline bilayer each segment of the DMPC molecule exhibits its own rotational freedom, in addition to its internal flexibility resulting from rotational isomerism. The results obtained in these calculations, although in general agreement with some experimental data, shed new light on the dynamical behaviour of phosphatidylcholine molecules in the bilayer membrane in the liquid-crystalline phase.

7

Local and global description of transport through membranes

84%

Grzywna Z. J.

Biophysics of Membrane Transport

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1992

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tom 11

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nr 1

8

Effect of heat stress on subcellular localization of Ca2 plus in tomato fruits

84%

Garbaczewska G., Choluj D., Starck Z.

Biological Bulletin of Poznań. Supplement

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1997

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tom 34

9

Molecular simulation studies of the interfacial region in lipid bilayers

67%

Pasenkiewicz-Gierula M., Rog T., Murzyn K.

Postępy Biologii Komórki. Suplement

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2001

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tom 16

10

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

67%

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

Cellular and Molecular Biology Letters

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2003

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tom 08

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nr 1

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.

11

Cysteine peptidases and their inhibitors in breast and genital cancer

59%

Agrawal A. K., Ekonjo G. B., Teterycz E., Zysko D., Grzebieniak Z., Milan M., Marek G., Siewinski M.

Folia Histochemica et Cytobiologica

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2010

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tom 48

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nr 3

12

Factors affecting intra and extracellular phospholipase A production by Salmonella typhi

59%

Punj V., Matta H., Kalra M. S.

Acta Microbiologica Polonica

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1994

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tom 43

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nr 2

Ograniczanie wyników

Red blood cell shape and deformability in the context of the functional evolution of its membrane structure

The carbamylation of proteins leads to alterations in the membrane structure of erythrocytes

Carbamylation of proteins leads to alterations in the membrane structure of erythrocytes

Molecular mechanisms of interaction between amphiphilic ammonium salts and membranes

Biophysical properties that control size and shape of extruded liposomes

Conformations, orientations and time scales characterising dimyristoylphosphatidylcholine bilayer membrane. Molecular dynamics simulation studies

Local and global description of transport through membranes

Effect of heat stress on subcellular localization of Ca2 plus in tomato fruits

Molecular simulation studies of the interfacial region in lipid bilayers

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

Cysteine peptidases and their inhibitors in breast and genital cancer

Factors affecting intra and extracellular phospholipase A production by Salmonella typhi