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The light scattering measure method for studying the kinetics of cell agglutination and aggregation under conditions of continuous and uniform stirring of suspension has been suggested.

The stabilizing effect of alpha-tocopherol on the enzymatic system of Ca2+ transport in sarcoplasmic reticulum (SR) membranes of rabbit skeletal muscle was studied. Exogenous fatty acids (e. g. arachidonic) cause destabilization of the enzymatic Ca2+ transport system by decreasing the thermal stability of Ca2+-dependent ATPase and the Ca2+-transport ability (Ca/ATP ratio) of SR membranes. Incorporation of alpha-tocopherol into SR membranes increases the thermal stability of the enzymatic Ca2+ transport system exposed to the damaging action of free fatty acids. Using differential scanning microcalorimetry, it was shown that arachidonic acid causes a shift of the maximum on the curve for the temperature dependence of specific thermal capacity of SR membranes towards the low temperature region. Under a combined action of arachidonic acid and alpha-tocopherol the position of the maxima on the temperature dependence curve for specific thermal capacity of SR membranes is close to the control value. A quantitative estimation of the values of molar enthalpies for SR membrane thermodenaturation demonstrated that the melting of Ca2+-dependent ATPase, the main intrinsic protein of SR membranes, is biphasic. The data obtained are discussed in terms of hypothetical mechanisms of protection of the enzymatic Ca2+ transport system against the damaging action of free fatty acids.

The prostaglandin F2 alpha (in concentration 1,4 or 14 microM) has been shown to induce the current fluctuations across the bilayers under the action on the planar bilayer membranes from the soya total phospholipids. The current fluctuations depend on the potential, their number expresses indistinctly and corresponds to the conductivity jumps across the bilayer about 5 pSm.

To elucidate the mechanisms of stabilization of biomembranes by tocopherols, the effect of alpha-tocopherol on thermal stability of rhodopsin in photoreceptor membranes of walleye pollock was studied. It was shown that alpha-tocopherol changed the rate constants of rhodopsin thermal denaturation neither in native, nor in peroxidised or treated with phospholipase A2 rod outer segments. Substitution of phospholipid microenvironment of rhodopsin in photoreceptor membrane by alpha-tocopherol did not result in stabilization of the visual pigment too.

Lecithin monolayer liposomes (1000 A in diameter) loaded with cytochrome c were placed into the external solution, in which O2 superoxide radicals were regenerated by the xanthine-xanthine oxidase system. The penetration of superoxide radicals across the liposomal membranes was followed by cytochrome c reduction in the interval volume of the liposomes. The effects of lipid membrane modifiers and temperature on this process were investigated. The results obtained were used for calculation of the permeability coefficients of bilayer lipid membranes for O(2) (P'O(2) = (7.6 +/- 0.3) . 10(-8) cm . s-1) or HO . 2(P'HO(2) = 4.9 x 10(-4) cm . s-1). The effect of the transmembrane electric potential (concentration gradient of H+, valinomycin) on the permeability of liposomal membranes for the superoxide radical was studied. The superoxide radical was down to penetrate across the bilayer lipid membranes in an unloaded state. Using an intramolecular cholesterol-amphotericin B-complex, the superoxide radicals were shown to penetrate across the bilayer lipid membranes, predominantly via the anionic channels.

The effect of pro-oxidant (ions of iron) and antioxidants (alpha-tocopherol, propylgallate) on hydroxylation of polycyclic hydrocarbon benz(a)-pyrene and the effect of hydroxylation process on lipid peroxidation have been studied. The role of allyl radicals formed in the fatty acid chains is discussed. The binding of oxygen radicals (formation of peroxy radicals) is regarded only as on of the possible reactions of the radical utilization. It is assumed that other reactions involving lipid (allyl) radicals, in particular, hydroxylation of benz(alpha)pyrene may occur in microsomal membranes.

It is believed that in lipid peroxidation in membranes an important role is played by unoxygenated hydrocarbon radicals whose movement within the hydrocarbon moiety of the membrane is through intra-and intermolecular relay rearrangements (H-shift). in membranes containing a high concentration of polyunsaturated lipids, mobility may be higher than the lateral diffusion of the lipids allowed by the microviscosity of the membrane. The action mechanism of antioxidants having a side hydrocarbon tail (e.g., tocopherols) rests upon the relay radical reaction, as a multistep process. The initial step is the relay transfer of unoxygenated free radical to the side hydrocarbon chain of antioxidant. In subsequent steps the aroxyl radical is formed by the intramolecular rearrangement of radical in an antioxidant molecule. Hence, the inhibitor interrupts the propagation chain in the membrane by the scavenge of unoxygenated hydrocarbon radical.

The effect of substances of different nature on the thermodynamic characteristics of dimyristoylphosphatidylcholine (DMPC) phase transition by the differential scanning microcalorimetry has been studied. The substances disposed in hydrophobic part of membrane--alpha-tocopherol, ubiquinone Q10, ionol and vitamin K3 cause the decrease of enthalpy and cooperativity of phase transition. The substances which have the side hydrocarbon chain (tocopherol and ubiquinone Q10) compared with ones without it (ionol and vitamin K3) and reduced quinones (Q10 and vitamin K3) compared with the oxidized ones have stronger influence on the enthalpy and cooperativity of transition. The inclusion of the local anesthetic dicaine disposed mainly in the zone of polar heads of phospholipids into DMPC membranes decreases the temperature of phase transition considerably and practically does not change the cooperativity. A possibility to use the method of differential scanning microcalorimetry to estimate the localization of membrane tropic substances within lipid bilayer is under discussion.

The dependence of the turbidity changes at 615 nm monobilayers liposomes from egg yolk lecithin in the presence of bromothymol blue on temperature and storage conditions has been investigated. It is established that the thermotropic properties of liposomes change irregularly and depend on the storage conditions. Sharp release of the bound dye at temperature above 35-37 degrees C is associated with thermotropic change in liposomes and the detected effects, with the change of orientation of the phosphorylcholine group.

It has been shown with reference to liver microsomes prepared in the presence and in the absence of alpha-tocopherol that structural alterations that may arise from the isolation procedure may affect interplay of carriers in NADP.H oxidation. Study of these alterations is of importance for understanding the influence of different factors of NADP.H oxidase on the involvement of NAD.H in benz(a)pyrene hydroxylation. If the electron transport via NADP.H-dependent flavoprotein is limited, the intense hydroxylation of benz(a)pyrene can be supported by means of chains involved in NAD.H oxidation. Studies have been focused on utilization of NAD.H in benz(a)pyrene hydroxylation and lipid peroxidation.

Data given propose two regimes of lipid radicals and oxygen utilization realized in microsomal and mitochondrial membranes. The first one, lipid peroxidation, i.e. interaction of lipid radicals and oxygen is an empty step. In converting this regime to the functional one NADPH-dependent lipid peroxidation is inhibited. A change of this regime to the functional one in microsome demand the presence of hydroxylation substrates. Setting lipid radical-dependent coupling apparatus on phosphorylation in mitochondria occur in the presence of ADP and Pi-phosphorylation substrates.

The amino acid sequence of D2 protein was compared with those of calcium binding proteins and receptor for calcium channel blockers in connection with the data showing the participation of Ca2+ in photosystem 2 electron transport and the inhibition of this process by calmodulin antagonists, calcium channel blockers and local anesthetics. Protein D2 possesses a pattern analogous to the "EF-hand" sites of the calcium binding proteins. Comparison of the amino acid sequence of the calmodulin fragment binding the phenothiazine type calmodulin antagonists with the amino acid sequence of D2 protein and calcium channel protein revealed a high degree of sequence identity. Common structural features take place also between the membrane spanning segment III of D2 protein, which contains the tyrosine residue (161), responsible for ESR-signal IIS, and the membrane segment IVS5 of calcium channel protein. A model explaining the mechanism of calcium function in the oxygen-evolving system is proposed.

The effects of pro-oxidants (Fe2+, CCl4) and antioxidants (alpha-tocopherol, propyl gallate) on hydroxylation of polycyclic hydrocarbon benz(a)pyrene and on the NADPH-cytochrome P-450-reductase reaction were studied. The role of allyl radicals formed in the fatty acid chains in discussed. The binding of O2 to free radicals, i. e. formation of peroxy radicals, is regarded only as a possible reaction of the radical utilization. It is assumed that other reactions involving lipid radicals, in particular, electron transfer from the flavoprotein to cytochrome P-480 may occur in microsomal membranes.

Heat accompanying the interaction between relaxed and contracted glycerinized fiber bundles of the striated muscles of rats and ATP was measured. Investigation of the interaction concerned both relaxed and preliminarily contracted bundles. As apparent from the thermokinetic curves, the interaction of ATP with the noncontracted bundles yields a peak of the thermal potency which coincides in time with the contraction process; no such effect was produced in case of preliminarily contracted fibers. The authors conclude that a direct interrelationship exists between the rate of ATPase activity and the conformation of actomyosin system.

A method based on changes in cell light scattering during agglutination is proposed for registration of cell agglutination in suspension. Unlike other methods of investigation of cell agglutination, our measurements are made under constant stirring and minimal stress tension in specially constructed cells. Possibilities of the method are shown upon registration of agglutination of trypsinized rabbit erythrocytes caused by PHA, Ca ions or by a sample containing lectin isolated from the fresh water algae Chara. The sensitivity of our method is higher, than that with the microtitration according to Tacashi, and makes it possible to investigate the agglutination process kinetics.

Data shown propose two regimes of lipid radicals and oxygen utilization realized in mitochondrial membranes. The first one--lipid peroxidation, i.e. interaction of lipid radical and oxygen is an empty step. In switching this regime to the functional one lipid peroxidation is inhibited. Setting L. -dependent coupling apparatus on phosphorylation in mitochondria takes place in the presence of ADP and Pi.

Hydroxylation of benz/a/pyrene might occur under decreased activity of NADPH-dependent reductase. In vivo a decrease in the activity of NADPH-dependent reductase did not influence apparently the intensity of benz/a/pyrene hydroxylation, which is maintained due to redistribution of reducing equivalents between oxygenase and oxidase systems in the cells. Anticarcinogenic effects of two different substances chrisene and ubiquinone are discussed taking into account possible normalization of NADPH- and NADH-dependent oxidative reactions in the cells.

The method of Na-dodecylsulfate electrophoresis in polyacrylamide gel demonstrated that the so-called tonoactomyosin of smooth muscles extracted from the muscle homogenate with salt media of low ionic power represented a complicated protein system into whose composition there was included a heavy myosin chain with the mol wt of 210000, premyosin subunit with the mol wt of 230000, actin, and, possibly, a number of other proteins. The extracts of low ionic power possessed Mg2+ and Ca2+ activated by ATP-ase activity. The premyosin subunit was also revealed in the extracts of low ionic power from the skeletal muscle homogenates. It is supposed that premyosin subunit was included into the enzymatic system responsible for the ATP-asic properties of the extracts of low ionic power from the homogenates of different types of muscles.

Mössbauer spectroscopy was used to investigate the distribution of iron in rat organs and its localisation in liver subcellular fraction. A 57Fe-sucrose complex solution was injected by 0.5 ml doses into tail veins of animals every day, during a 6-day period. Mössbauer spectra were measured in spleen, blood, liver and liver subcellular fractions. The mössbauer spectrum of a spleen sample has two symmetrical doublets, one with delta = 0.6 mm/s and delta = 0.7 mm/s, and the other with delta = 1.0 mm/s and delta = 2.35 mm/s. The Mössbauer spectrum of blood has parameters which are close to those for carboxyhemoglobin and oxyhemoglobin complexes. After the addition of sodium citrate, the proportion of the carboxyhemoglobin complex increases. The Mössbauer spectrum of liver has a two-component pattern with two symmetrical doublets, the first with delta = 0.6 mm/s and delta = 0.63 mm/s and the second with delta = 1.4 mm/s and delta = 3.45 mm/s. The first component, which was identified as ferritin, is present in all subcellular fractions (800 x gav sediment fraction, mitochondrial/lysosomal, microsomal and supernatant fractions), with its greatest content in microsomal fraction. After the addition of NaBH4 to mitochondrial/lysosomal fraction, about 20% of the iron contained in ferritin was reduced. In the Mössbauer spectrum this is reflected by an appearance of a doublet with delta = 0.85 mm/s and delta = 3.7 mm/s.

Ca2+ ions at low concentration (10(-4)-10(-5) M) when added to ultracentrifugates of sarcoplasmic proteins with minimal content of sarcoplasmic reticulum fragments completely prevent protein gelatinization or gels, formed in these conditions, quickly dilute. Ca2+ ions at the concentration of 10(-3) M prevented in these conditions gelatinization in all the cases studied. Strong gels of sarcoplasmic proteins are formed afterwards in weak acid (pH 6.1-6.75), neutral (pH 7.0) and weak alkaline (pH 7.25-7.45 and higher) media. It is suggested that gelatinization of sarcoplasmic proteins is closely related with the development of plastic tonus, obturatory muscle function and viscous after-effect.

The photoinduced electron transfer at low temperatures in phospholipide membranes (liposomes) containing chlorophyll and 3 X 10-docsilpalmitate has been investigated. The reduction of 3 X 10-docsilpalmitate was estimated by ESR spectrometry. When diffusion movement of the molecules in membranes was blocked by low temperatures the photoinduced electron transfer has been found. The mechanism of these phenomena were analyzed on the base of donor-acceptor interaction through sigma bonds in hydrocarbon bridged donor-acceptor complexes. The separation of charges in these complexes is regarded as occurs by the migration of a hole along the hydrocarbon system. An approximate estimate of the charge mobility in the saturated hydrocarbon side chain of chlorophyll and activation energy of these movement was obtained.

The mechanism of inhibition by local anaesthetics of the procaine group of electron transport at the donor site of photosystem II (PS II) from pea chloroplasts was investigated. It was found that besides the inactivation of the O2 release system the anaesthetics used at one order of magnitude lesser concentration exert an uncoupling effect. With a rise in pH the inhibiting activity increases; however, this process is not coupled with the protonophore effect but is due to the generation of a neutral form of the amine. The increment of the inhibiting activity of the anaesthetics in the course of deprotonation seems to be regulated by changes in the coefficient of distribution between the membrane and the aqueous phase. The rate of inactivation of the H2O-dissociating complex increases considerably upon illumination. Electron transport through PS II in anaesthetic-treated chloroplasts in restored by diphenylcarbaside, but not by hydroxylamine. It is concluded that the anaesthetics induce the inhibition by interacting with the electron carrier. The role of the Ca2+--calmodulin-like protein in the functioning of the electron transport chain of PS II is discussed.