[Application of phosphorescent probes in investigations of model and biological membranes]. / Primenenie fosforestsentnykh zondov dlia issledovaniia model'nykh i biologicheskikh membran.

Possibility of using phosphorescent probes for membrane investigations was analysed on lecithin liposomes and rat liver microsomes taken as an example. It was shown that one quencher molecule on 10(4) lecithin molecules is sufficient for experimental registration of diffusion-controlled quenching of erythrosine phosphorescence by stable nitroxide radicals. It is possible to study the diffusion processes with D = 10(-5) divided by 10(-9) cm2s-1. Application of quenchers of different polarity allows to make a conclusion that the phosphorescent probe erythrosine is localized in liposomes in the region of polar heads of phosphatidyl choline. It was determined from the rate of phosphorescence quenching by radicals that the membrane microviscosity in this region at 20 degrees C equals approximately 1 puas. The coefficient of erythrosine lateral diffusion in liposomes estimated from their self-quenching equals 1,1 x 10(-8) cm2s-1. In the microsome erythrosine is localized in hydrophobic parts of proteins and is not accessible for the quencher molecules.

[Reduction of spin labels with ascorbic acid in solution and on biomembranes]. / Vosstanovlenie spinovykh zondov askorbinovoi kislotoi v rastvore i na biomembranakh.

Dependence of the rate of nitroxyl radical reduction with ascorbic acid upon pH, ionic force, temperature, type of radical and dielectric constant of the solvent is reported. The factors mentioned are essential for interpreting the results obtained for biomembranes. It is shown that under physiological pH the reduction is determined by ascorbic acid monoanion and unprotonated radical interaction. In acid environment the reaction involves more complicated mechanisms. In the presence of microsome membranes the negative radical R5-COO- reduction proceeds in two steps. The first one is in power more fast than in water solution. The membrane influence was insignificant in case of the uncharged R6- = O and [Formula: see text] and radical R6-NH2 which is able to form the cation R6-NH3+.

[Study of spin-labeled microsomal membrane proteins by their reaction with ascorbic acid]. / Izuchenie spin-mechennykh belkov membran mikrosom po reaktsii s askorbinovoi kislotoi.

Kinetics of the reduction of nitroxyl radicals bound to SH-groups of microsome membrane proteins by ascorbic acid was investigated. The reduction involves two steps. During the first quick step mainly the radicals with weak immobilization located on the membrane surface are reduced. At the second slow step more immobilized radicals located in hydrophobic membrane regions take part in the reaction. A kinetic analysis of the process showed that the slow step is not determined by the slow movement of protein or its fragments, for instance, from the membrane depth to its surface, and apparently is conditioned by lower ascorbic acid concentration in the membranes.

[Extraction of cholesterol from vessel walls by surface-active agents and organic solvents]. / Ekstraktsiia kholesterina iz stenki sosuda poverkhnostno-aktivnymi veshchestvami i organicheskimi rastvoriteliami.

Low concentrations (0.1--1.0%) of surface-active substances Tween-20, Triton X-100 and sodium deoxycholate were shown to extract 20--40% of cholesterol from dog vessel wall. Dioxane was effective at high concentrations (80--100%). As contrast to dioxane, ethanol extracted up to 20% of cholesterol at low concentrations (10--20%). The thickened intima of the atherosclerotic vessel is the significant barrier for the extraction of cholesterol.