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1

The Equilibrium of Phosphatidylcholine-Sphingomyelin in a Monolayer at the Air/Water Interface

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

Polish Journal of Chemistry

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2008

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Vol. 82, nr 12

2323-2330

EN

Monolayers of either phosphatidylcholine (PC) or sphingomyelin (SM) or their mixtures (PC-SM) were investigated at the air/water interface. The surface tension values of pure and mixed monolayers were used to calculate the pi-A isotherms. The theory of equilibrium between components of monolayers at the air/water interface has been developed in order to obtain the stability constant of the PC-SM complex. We considered the equilibrium between PC, SM and the PC-SM complex on the basis of derived equations. We established that phosphatidylcholine and sphingomyelin formed a 1:1 complex, with the stability constant equal to KAB = 3.20x105 m2 mol-1.

2

Impact of the charge density of phospholipid bilayers on lubrication of articular cartilage surfaces

Pawlak Z., Kotynska J., Figaszewski Z. A., Oloyede A., Gadomski A., Gudaniec A.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 23, nr 1

47-50

EN

Purpose: We attempt to answer the question how some changes in acid - base equilibrium have an impact on the charge density of a phospholipid bilayer formed during lubrication occurring at articular cartilage surfaces. Design/methodology/approach: Liposomes have been used to mimic biological phospholipid membranes on articular cartilage surface where proteins are bounded, ions are transported, energy is transducted, and cellular processes are taking place. The charge density of the membrane was determined as a function of pH and electrolyte concentration from the microelectrophoretic method. Liposome membrane has been prepared as an aqueous solution of NaCl under various pH conditions. Microelectrophoresis was used to examine the local acid-base equilibrium of the electrolytes with the membrane surface, which can be considered to be an interface of phospholipids in articular cartilage. Findings: The effects of the adsorption of ions (H+, OH- ; Na+, CI-), which are present in solution upon electric charge of the liposome membrane assembled of phosphatidycholine (PC), have also been found to exhibit pH-responsive (quasi-periodic) behavior. Research limitations/implications: We hypothesized that the acid-base dissociation behavior in phospholipid bilayers of articular cartilage is a key to understanding biolubrication processes. For example, similar previous investigators found that the behavior of a multilayer made of polyisopeptide/hyaluronic acid depends on some of the surface properties such as film thickness, surface friction, surface wetness and swelling conditions. Future work should consider the adsorption of polyelectrolyte ions, e.g., the glycoprotein lubricin and hyaluronan, at the liposome membrane surface involved, assumed that besides the H+ and OH- ions, the polyelectolyte ions were also engaged. Originality/value: This liposome membrane is a model for phospholipid bilayers and will be applied for the investigation of polyelectrolyte ions, e.g. lubricin, in articular cartilage conditions. We demonstrate that knowledge on the acid-base processes on charged surface is the key to understanding phenomena occurring at interfaces in human joints lubrication, thus pointing to the biolubrication as a charged interface-controlled process.

3

Isolation and analysis of phospholipids

Ostrowska J., Skrzydlewska E., Figaszewski Z. A.

Chemia Analityczna

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2000

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Vol. 45, No. 5

613-629

EN

Different chromatographic methods used for the determination of phospholipids isolated from natural biological membranes have been described. A particular attention is given to the choice of the HPLC technique, and to the separation conditions: stationary phase, composition of mobile phase and detectors.

PL

W artykule dokonano przeglądu literatury na temat izolacji fosfolipidów z błon biologicznych. Szczególną uwagę zwrócono na wykorzystanie do tego celu techniki HPLC, na warunki rozdziału: fazy stacjonarne, skład faz ruchomych oraz detektory.

4

HPLC study of the modification of haemoglobin by formaldehyde

Ostrowska J., Roszkowska A., Skrzydlewska E., Figaszewski Z. A.

Acta Chromatographica

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1999

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No. 9

87-96

EN

Formaldehyde is known to react with proteins. The effect of formaldehyde on the total charge and on the tryptic map of haemoglobin has been analysed by HPLC. The effect of methanol intoxication on the total charge of rat haemoglobin was also determined. The total charge of haemoglobin was examined on a Mono Q column by gradient elution with solutions of Tris–HCl and Tris–HCl–NaCl. Tryptic maps were determined on a C18 column by gradient elution with solutions of TFA–water and TFA–acetonitrile–water. Formaldehyde in vitro and methanol intoxication resulted in prolonged retention of haemoglobin. Formaldehyde also reduces the susceptibility of haemoglobin to trypsin hydrolase which leads to a reductions in the magnitudes of peaks in the tryptic map.