Effect of trypsin microenvironment on the rate constants of elementary stages of the hydrolysis reaction of N α-Benzoyl-L-arginine ethyl ester

The hydrolysis reaction of N ^α-benzoyl-L-arginine ethyl ester catalyzed by trypsin from pig pancreas was comparatively studied in an aqueous buffer solution and in the system of reversed micelles of Aerosol OT in octane (pH 8.5) to determine the mechanisms of influence of the enzyme microenvironment on the rate constants of the elementary stages of the enzymatic reaction. The temperature dependences of the catalytic constant k _cat and the rate constant of the second order k _cat/K _m (s, catalysis efficiency) allowed the determination of the rate constants and the activation energy of elementary stages of the enzymatic reaction. It was revealed that a decrease in the efficiency of catalytic action of trypsin in reverse micelles in comparison with an aqueous solution is first of all determined by a decrease in the rate constant of formation of the enzyme-substrate complex k ₁. Possible mechanisms of the effect of the microenvironment on the elementary stages of catalytic action of the enzyme are discussed.     

The ability of E. coli DNA methylases to modify denatured DNA

Adenine and cytosine DNA methylases from different strains of E. coli are able to methylate denaturated and single-stranded DNAs.     

The effects of near infrared radiation on rats assessed by succinate dehydrogenase activity in lymphocytes in blood smears

The biological effects of near infrared radiation (850 nm) modulated by an acoustic frequency of 101 Hz were studied. The study was conducted on rats; the effect was registered by succinate dehydrogenase activity in lymphocytes in blood smears after the administration of an activating dose of adrenaline, which simulates the state of the organism at early stages of a pathogenic action (stress). A pronounced regulating effect of infrared radiation on the activity of succinate dehydrogenase in animals that were activated by adrenaline was shown. Infrared radiation has a normalizing effect via the reduction of the degree of inhibition or activation of the enzyme induced by adrenaline and has no effect on the control animals. Thus, by modulation of the activity of succinate dehydrogenase, infrared radiation regulates energy production in mitochondria that is provided by the most potent oxidation substrate, viz., succinic acid; the effect is especially pronounced under stress.     

Chaperone-like activity of β-casein and thermal stability of alcohol dehydrogenase

Correlation between structural peculiarities of beta-casein and its chaperon-like activity was investigated using the recombinant forms of the protein containing the cysteine residues in the polypeptide chain. Aggregation of native and modified forms of β-casein was studied, as well as their chaperon-like activity towards alcohol dehydrogenase thermal aggregation. It has been shown that dimeric and oligomeric forms of β-casein, which are formed due to intermolecular disulfide bonds, significantly differ in their physicochemical and chaperon-like properties from monomeric forms. The thermal stability of alcohol dehydrogenase has been found to depend on the β-casein concentration.     

States of succinate dehydrogenase in the organism: Dormant vs. hyperactive (pushed out of equilibrium)

Using an original cytobiochemical method to study oxidation in mitochondria, preserving their native network organization within cells in a blood smear, we have revealed a hyperactive state of succinate dehydrogenase that arises in the organism under physiological stress. This is generally consistent with the notion of non-equilibrium state of enzymes during their activity. The mechanism moderating the succinate dehydrogenase hyperactivity is based on full-fledged functioning of α-ketoglutarate dehydrogenase, sup-ported by oxidation of isocitrate.     

Importance of preserving the biophysical organization of isolated mitochondria for revealing their physiological regulation

A method has been elaborated that preserves the mitochondrial-reticular network in lymphocytes by immobilization of a blood smear on glass and its subsequent incubation in a medium close in composition to the physiological one. Physiological responses of mitochondrial respiration to excitation in the organism are well pronounced on these preparations. Detection of early responses of mitochondria to pathogenic agents in the organism is a topical problem of basic and medical research, since such alterations play a leading role in the development of pathological states.     

Isolation of Ca 2+-activated photoprotein obelin from Obelia longissima and its use for the recording the outflow of Ca 2+ from fragmented sarcoplasmic reticulum of skeletal muscles

A high-active stable preparation of obelin has been obtained from the luminescent hydroid Obelia longissima. The preparation is appropriate for determining free Ca2+ in the physiological range of its concentrations Obelin is shown possible to be used to record the processes of Ca2+ release from vesicles of the sarcoplasmic reticulum. In this case a rapid initial phase of Ca2+ outflux replaced by a slower one has been registered. A sharp increase of luminescence caused by the appearance of free Ca2+ in the medium has been registered under the effect of agents either increasing permeability of sarcoplasmic reticulum membranes for Ca2+ (A23187) or destroying the membrane (ethanol, triton X-100). The observed effects are confirmed, a radioactive label being used.     

The Effect of Aerobic Methylotrophic Bacteria on the in vitro Morphogenesis of Soft Wheat (Triticum aestivum)

The effects of four aerobic methylotrophic bacteria on the morphogenesis of soft wheat (Triticum aestivum) were studied in vitro using immature embryos as explants. The inoculation of the embryos with methylotrophic bacteria led to their stable colonization with the bacteria. The colonization of the explants with the strains of Methylobacterium sp. D10 and Methylophilus glucoseoxidans stimulated the formation of morphogenic calli and shoots and also promoted development of the regenerated plants. These regenerated plants manifested bright green leaves and a well-developed root system. The colonization of immature wheat embryos with methylotrophic bacteria can be employed as a tool for raising the efficiency of genetic transformation of various wheat cultivars.