The Role H-Bonding and Supramolecular Structures in Homogeneous and Enzymatic Catalysis

The article analyzes the role of hydrogen bonds and supramolecular structures in enzyme catalysis and model systems. Hydrogen bonds play a crucial role in many enzymatic reactions. However, scientists have only recently attempted to harness the power of hydrogen bonds in homogeneous catalytic systems. One of the newest directions is associated with attempts to control the properties of catalysts by influencing the "second coordination sphere" of metal complexes. The role H-bonding, and the building of stable supramolecular nanostructures due to intermolecular H-bonds, based on catalytic active heteroligand iron (Fe) or nickel (Ni) complexes formed during hydrocarbon oxidations were assessed via the AFM (Atomic-force microscopy) method, which was proposed and applied by authors of this manuscript. Th is article also discusses the roles of hydrogen bonds and supramolecular structures in oxidation reactions catalyzed by heteroligand Ni and Fe complexes, which are not only effective homogeneous catalysts but also structural and functional models of Oxygenases.

[The Effect of NT-1505 on a Membrane Structure of Endoplasmic Reticulum in vivo]

The effect of neuroprotector NT-1505 on endoplasmic reticulum membranes was studied. It was shown that the dynamics of changes in lipid and near-protein areas microviscosity of endoplasmic reticulum membranes at drug administration is of an antibate nature. This points to the absence of pathological disturbances in the membrane structure. Membrane microviscosity was measured by electron paramagnetic resonance spin labeling of 2,2,6,6-tetramethyl-4-capryloyl-oxylpiperidine-1-oxyl (lipid probe) and 5,6-benzo-2,2,6,6-tetramethyl-1,2,3,4-tetrahydro-γ-carboline-3-oxyl (near protein probe). To obtain more complete information about changes in membrane structure under the action of neuroprotector NT-1505 the temperature dependence of rotational diffusion correlation time was measured in the temperature range of 283-317 K (10-44 degrees C). The two structural transitions were characterized for both areas of .membranes of control group in temperature intervals 16-20 degrees C and 32-38 degrees C which were still present after NT-1505 introduction. Therefore, NT-1505 has no significant effect on membrane structure of the endoplasmic reticulum.

[Studying the effect of Dimebon and NT-1505 on microviscosity of mice brain synaptosomal membranes in vivo by EPR spin labeling method]

In this work membrane fluidity alterations in synaptosomes, isolated from mice brain tissue, at chronic administration of neuroprotectors Dimebon and NT-1505 in vivo were studied. Membrane microviscosity was measured by electron paramagnetic resonance spin labeling of 2,2,6,6-tetramet-hyl-4-capryloyl-oxylpiperidine-l-oxyl (lipid probe) and 5,6-benzo-2,2,6,6-tetramethyl-1,2,3,4-tetrahydro-gamma-carboline-3-oxyl (near protein probe). It was shown that the neuroprotectors Dimebon and NT-1505 affect a membrane structure. Despite the difference in membrane structures, fluidity of the lipid bilayer in time returned to control values.

[Effects of low doses of essential oil on the antioxidant state of the erythrocytes, liver, and the brains of mice]

We studied the effects of essential oil from oregano and clove and a mixture of lemon essential oil and a ginger extract on the antioxidant state of organs in intact and three experimental groups of Bulb mice. We found that the essential oil was an efficient in vivo bioantioxidant when mice were treated with it for 6 months even at very low doses, such as 300 ng/day. All essential oil studied inhibited lipid peroxidation (LPO) in the membranes of erythrocytes that resulted in increased membrane resistance to spontaneous hemolysis, decreased membrane microviscosity, maintenance of their structural integrity, and functional activity. The essential oil substantially decreased the LPO intensity in the liver and the brains of mice and increased the resistance of liver and brain lipids to oxidation and the activity of antioxidant enzymes in the liver. The most expressed bioantioxidant effect on erythrocytes was observed after clove oil treatment, whereas on the liver and brain, after treatment with a mixture of lemon essential oil and a ginger extract.

[Investigation of changes in fluidity of brain membranes in mice bearing experimental Alzheimer's disease using spin labeling electron paramagnetic resonance]

Changes in fluidity of membranes isolated from the microsomal and crude synaptosomal fractions which were obtained from forebrain tissue of mice bearing experimental Alzheimer's disease induced with olfactory bulbectomy were studied. Membrane microviscosity was measured by electron paramagnetic resonance with 2,2,6,6-tetramethyl-4-capryloyl-oxypiperidine-1-oxyl and 5,6-benzo-2,2,6,6-tetramethyl-1,2,3,4-tetrahydro-gamma-carboline-3-oxyl as spin labeling. Phasic alterations in relative fluidity were found during the development of experimental Alzheimer's disease pathology. These changes correlate with the stages of "clinical" features. Main abnormalities were related to structural changes in near-protein region of the lipid bilayer.

[Interrelation between structural state, physicochemical properties and lipid composition in microbial cells]

We performed complex investigations of antioxidant properties and the lipid composition of the five gram-negative bacteria depending on the cultivation season. Structural state, the lipid composition and physicochemical properties of lipids of the three gram-negative bacteria (Renobacter vacuolatum, Flectobacillus major WKM 869, Pseudomonas fluorescens) during their growth and mycelium of four species of the xylotrophic basidiomycetes (Panus tigrinus IBK-131, Fomes fomentarius M71, Laetiporus sulfureus M131, Piptoporus betulinus M60) during the lag phase were also studied. Changes in the composition of the lipid component in the studied bacteria led to considerable structural rearrangements in their membrane system during the growth of bacteria. It is shown that more hydrophilic regions of the lipid component are of paramount importance in maintaining the fluidity of the entire lipid bilayer in the basidiomycete mycelium. The scale and direction of the revealed interrelations between rotational correlation times of probes and the lipid composition depend both on localization of the probe in membrane and the composition and physicochemical properties of the microorganism lipids.

[Changes in fatty acid composition in the brain and liver in aging mice of high cancer risk AKR strain and effect of savory essential oil administration on leukemic process]

Age-related alterations of fatty acid composition in liver and brain of AKR mice was investigated. The effect of savory essential oil (Satureja hortensis L.), added with drinking water on fatty acid composition in these organs and the processes of lipid peroxidation in erythrocytes were estimated. It was found that during aging the percentage of saturated fatty acids and polyunsaturated fatty acids decreased while monounsaturated fatty acids increased. The development of leukemia was accompanied by the increase of saturated and polyunsaturated fatty acids percentage and a decrease of monounsaturated fatty acids amount. In the liver aging caused the increase in the percentage of saturated fatty acids, the decrease of monounsaturated fatty acids, while the amount of polyunsaturated fatty acids was not changed. Leukemia (after 8 month) was accompanied by the increase of percentage of monounsaturated fatty acids and the decrease in the amount of oleinic and docosohexaenic acids. The intake of savory essential oil was accompanied by intensification of polyunsaturated fatty acids synthesis in mice liver and reduction of lipid peroxidation products content.

[The effect of volatile antioxidants of plant origin on leukemogenesis in mice]

The effect of savory essential oil added with drinking water (150 ng/ml) or with feed (2.5 microg/g) on the lifetime of AKR mice and the parameters of oxidative stress in animal blood were investigated. It was found for the first time that long-term administration of an essential oil in low doses increased the average lifetime of mice by 20-35% and was accompanied by a decrease in the hemolysis level and the content of lipid peroxidation products in erythrocytes of mice, as well as alteration in the structural state of their membranes and stabilization of polyunsaturated fatty acids level in mice liver cells.

[Effect of low doses of phenozan on lactate dehydrogenase and microviscosity of microsomal membranes of brain cells in mice]

It was shown that low doses of phenozan (10(-17), 10(-14), 10(-11), 10(-5) mol/kg) caused changes in kinetic parameters Vmax, Km of LDG and microviscosity in various ranges of microsomal membranes of brain cells. It is suggested that the effect of phenozan on the structure of bilayer membrane is important for binding LDG with membranes.

[New aspects of of the effects of low intensity radiation]

In paper the new aspects of action regularity of ionizing radiation of low intensity on the biophysical and biochemical characteristics of bio-objects and populations are considered. From the point of view of breaking the connection between occurrence of damages and work of systems of restoration at low intensity irradiation, are described the dose dependence of different types--from threshold up to extreme and a plateau curve, differing among themselves only by a parity of these processes. The features of action of low intensity irradiation on bio-objects and populations--change of structure of a population, sensitivity to action of external stimulus, force of connections between the elements of regulatory systems--allow to consider the low intensity irradiation as the factor capable to cause unpredictable transition of quasistationary systems in new status.

[The characteristics of the biological action of low doses of irradiation]

Biochemical, biophysical and functional properties of the genetic and membrane apparatus of the cell were considered activity and regulatory properties of the membrane and cytosolic enzymes of organs and tissues of mice exposed to radiation in the wide range of doses of 6 to 1800 mGy with the radiation intensity of 4.1 x 10(-3) and 41 x 10(-3) mGy/min. It was shown that the dose-dependence of changes in the investigated properties is of non-linear polymodal (bimodal) nature. The value of the maximum and the dose at which the latter was observed depend on the object's nature, radiation intensity and time passed after irradiation. An essential factor is that sensitivity of molecules, cells, organs and animals exposed to low-dose radiation to other damaging effects changes. The explanation is given in terms of the changes in the relation between the quantity of damages and the activity of reparation systems induced by low-dose irradiation.

[Structural and biochemical parameters of blood components of mice after gamma irradiation with small doses of different intensity]

The complex study on the low gamma-irradiation on the structural feature of lymphocyte DNA and lipid peroxidation (LPO) regulatory system parameters in mice blood was carried out depending on irradiation intensity. It was found that DNA alkaline elution rate constants, viscosity of the different regions of erythrocyte membranes and LPO products content in mice blood plasma varied nonlinearly depending on dose or dose rate. The proportion of the damage types and the range of the DNA structural changes substantially differ depending on the gamma-irradiation dose and its intensity. It is considered that the proportion of the DNA and membrane damage and repair can change depending on radiation dose and dose rate.

[Effect of the functional groups of tocopherol molecules on lipid viscosity of mitochondria]

The influence of tocopherol and its analogue (oxychroman) on the microviscosity of mitochondrial lipids was studied, using spin labels. The viscosity of the lipid bilayer was shown to enhance with the increase in the antioxidant content in the membrane. Small concentrations of alpha-tocopherol (10(-5)-10(-6) mol/l) were shown to increase, while large concentrations (10(-3)-10(-4) mol/l) decreased the fluidity of the lipid bilayer. The influence of alpha-tocopherol on fluidity of the lipid bilayer depending on its concentration could be realized in two ways: by direct influence on the lipid bilayer and via reception. It was shown that alterations in the viscosity of the lipid bilayer depend on chroman cycle of tocopherols, while the temperature of structural transfer and effective energy of activation depend on the lateral phytyl chain.

[Effect of irradiation on microviscosity of the cellular nuclear membrane of tumor and liver of tumor-carriers]

Spin probe analysis was carried out of changes in microviscosity of the nuclear membranes of the cells of tumor and liver of tumor-carriers with developing Ehrlich ascite carcinoma (EAC) different time after irradiation with lethal doses (650 r). Two iminoxyl radicals mainly localized in a lipid bilayer and in the membrane lipid layers adjacent to protein were applied. The pattern and level of changes in microviscosity of different nuclear membrane regions point to different response to irradiation of the cells of the tumor-carrier organ and of the tumor, both in viscosity properties and in the changes in lipid-protein relationships. A significant contribution to the total changes of the nuclear membrane microviscosity was made by the lipid layers adjacent to proteins. It is responsible for different reactions of the nuclear membranes of liver cells in tumor-carriers and in healthy animals, and also for a significant (3-fold) dilution of the nuclear membrane of EAC cells after irradiation. It is shown that temperature relationship of the times of rotative correlation of both probes is more pronounced in EAC cells of irradiated tumor-carriers than in the liver.

[System regulating lipid oxidation and the state of the nuclear membrane during tumor growth]

Changes of antioxidative activity (AOA), lipid composition and membrane structure in tumour cell nuclei and in the liver of tumour-carrier during the development of Ehrlich ascite carcinoma (EAC) were studied. On the basis of the data obtained the work of physico-chemical system of oxidative reactions in lipids was analysed. This control system involves a relationship between AOA changes, lipid composition, their oxidative ability and the nuclear membrane structure. It was shown that with EAC development in the cell nuclei of the tumour-carrier liver the control system under study is functioning like in the normal state. In EAC cell nuclei in the course of tumour growth there proceeds a change in the relationship AOA -- lipid composition -- membrane structure, the primary disturbance in the system appearing evidently within the link AOA -- lipid composition.

[Thermoinduced structural changes in the membranes of animal organs following administration of antioxidants and during growth of malignancies]

By means of weak-bound spin probes--stable iminoxyl free radicals differing in the level of hydrophobity there were studied thermoinduced structural transitions in the membranes of cell organells of animal liver after intraperitoneal injection of antioxidants and in the course of malignant growth, and in the nuclear membranes of Ehrlich ascite carcinoma as well. It has been found that during the growth of Ehrlich ascite carcinoma changes in rotationary mobility of probes in cell nuclei isolated from the liver of tumour-carrying animal are similar to the changes observed after antiocidants injection. A different pattern is observed in tumour cells. The membranes of ascite cell nuclei are characterized by a weak dependence of tau c on temperature for both probes. Within the temperature range studied no characteristic structural transitions proceeding in the nuclei of intact animals are observed.

[Spin label study of microviscosity and structural transitions in cell membrane lipids and proteins. I. Heat-induced structural changes in cell nuclei of mouse organs in normal conditions]

With the help of weakly bound spin probes the effect of temperature on structural transitions of protein and lipid components in the nuclei membranes of different organs of intact mice has been studied. Microviscosity of lipids in the membrane is found to differ sharply from proteins. Found by both probes breaks on Arrhenius curve of the correlation time dependence on reverse temperature within the temperature range of 25degreesC--27degreesC and 40degreesC-43degreesC seem to be connected with structural reconstructions of the whole membrane. The results obtained according to the behaviour of probes are identical for the nuclei of different organs.