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1

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

100%
Pieniazek A., Gwozdzinski K.
Cellular and Molecular Biology Letters
|
2003
|
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.
2

Changes in red blood cell membrane structure in patients with chronic renal failure

100%
Gwozdzinski K., Janicka M., Brzeszczynska J., Luciak M.
Acta Biochimica Polonica
|
1997
|
tom 44
|
nr 1
The properties of red blood cell membranes in patients with chronic renal failure were investigated using electron paramagnetic resonance spectroscopy. Using spin traps, 5,5-dimethylpirroline-l-oxide and N-tert-butyl-a-phenylni- trone, we found generation of hydroxyl radicals in the blood of patients with chronic renal failure after 20 min of regular hemodialysis. The physical state of membrane proteins and membrane osmotic fragility and reductive properties of red blood cells were studied. The increase in the relative correlation time of 4-(2-iodoacetamido)-2,2,6,6-tetramethylpiperidine-l-oxyl in­dicates the immobilization of membrane protein molecules in erythrocytes of chronic renal failure patients. The decrease in membrane protein mobility was observed in whole blood incubated with tert-butylhydroperoxide, regardless of the presence of iron. We found that the addition of ferrous ions did not aggravate profound changes in membrane proteins induced with tert-butylhy­droperoxide. We also demonstrated higher osmotic fragility of erythrocytes in the patients with renal failure as compared to normal subjects.
3

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

80%
Subczynski W. K., Wisniewska A.
Cellular and Molecular Biology Letters
|
1996
|
tom 01
|
nr 4
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.
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