Interaction of the prion protein fragment PrP 185-206 with biological membranes: effect on membrane permeability.

Amyloids are proteinaceous aggregates related to the so-called conformational diseases, such as Alzheimer's and prion diseases. The cytotoxicity of amyloids may be related to the interaction of the amiloidogenic peptides or proteins with the cell membrane. In order to gain information on the physico-chemical effects of amyloids on membranes, we have studied the interaction of the human prion amyloidogenic fragment PrP 185-206 with negatively charged model membranes.

The interaction of PVP complexes of gossypol and its derivatives with an artificial membrane lipid matrix.

In this paper, we present the results of a study on the membrane-active properties of gossypol, its derivatives and their polyvinylpyrrolidone complexes as assessed by differential scanning calorimetry and by the fluorescent probe method. The latter revealed the change in polarization of the incident radiation caused by the action of the polyphenol on the artificial membrane lipid matrix.

The immobilization of gossypol derivative on N-polyvinylpyrrolidone increases its water solubility and modifies membrane-active properties.

The conjugate of the gossypol derivative megosin (1) with N-polyvinylpyrrolidone named rometin (2) was synthesized. The effects of 1 and 2 on the structure and permeability of human erythrocytes and rat liver mitochondria were compared. Compound 1 induced dose-dependent erythrocyte hemolysis and increased mitochondrial permeability, with concomitant changes in membrane structure as determined by ESR and fluorescence anisotropy methods.

Chiral macroaggregates of LHCII detected by circularly polarized luminescence in intact pea leaves are sensitive to drought stress.

Circularly polarized chlorophyll luminescence (CPL) was recently shown to be an effective tool for the study of chiral macroaggregate formation of the light-harvesting chlorophyll a/b pigment-protein complexes (LHCIIs) in isolated chloroplasts. The CPL measuring system was modified to study green leaves. Spectral and intensity features of pea leaf CPL signals suggested that CPL indeed detected chiral macroaggregates.

The role of membrane structure in activation of mitochondrial phospholipases. 2. Mechanism of crambin action on the activities of mitochondrial membrane phospholipases and microviscosity.

Effects of crambin on the phospholipase activity, lipid peroxidation and structure of mitochondrial membranes have been investigated. Crambin has been shown to inhibit lipid peroxidation and phospholipase activity induced by Ca2+ and freezing-thawing of mitochondria. As shown by ESR studies, these effects are based on the ability of crambin to cause changes in mitochondrial membrane structure.