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Applied Biochemistry and Microbiology (v.39, #6)
Methionine Sulfoximine and Phosphinothrycin: A Review of Their Herbicidal Activity and Effects on Glutamine Synthetase by Z. G. Evstigneeva; N. A. Solov'eva; L. I. Sidel'nikova (pp. 539-543).
Derivatives of methionine sulfoximine (MSO) and phosphinothrycin (PPT), which are analogues of glutamate, exhibit selective herbicidal activity. This effect is accounted for by impairment of nitrogen metabolism, resulting from inhibition of its key enzyme in plants, glutamine synthetase (EC 6.3.1.2). Inhibition of the enzyme causes ammoniac nitrogen to accumulate and terminates the synthesis of glutamine. Changes in the content of these two metabolites (excess ammonium and glutamine deficiency) act in concert to cause plant death. However, low concentrations of MSO, PPT, and their metabolites produce an opposite effect: glutamine synthetase is activated, with concomitant stimulation of plant growth and productivity. The mechanisms whereby MSO and PPT affect glutamine synthetase activity are discussed in the context of nitrogen metabolism in plants.
Identification of Catalytically Active Groups in Inulinase from Bacillus polymyxa 722 by N. A. Zherebtsov; I. N. Abramova; S. A. Shelamova; T. N. Popova (pp. 544-548).
Inulinase from Bacillus polymyxa 722, hydrolyzing a polyfructosan inulin, was studied. The dependence of inulinase activity on pH, measurements of pK value, calculation of the ionization heat, photoinactivation with methylene blue, and inhibition with p-chloromercuribenzoate suggest that the active center of this enzyme contains imidazole and sulfhydryl groups. A possible mechanism underlying the cleavage of β-2,1-fructoside bonds in the inulin molecule by inulinase is considered.
Isolation and Purification of Bovine Testicular Hyaluronidase by A. K. Barsukov; O. V. Kozhevnikova; A. V. Khokhryakova (pp. 549-552).
We developed a one-step method for the chromatographic purification of hyaluronidase extract on Sepharose Blue, which produced the purified enzyme with a high yield (95%). Purification of hyaluronidase allowed us to obtain biological preparations standardized in protein composition and enzyme activity, which are useful for basic and applied studies.
Noncompetitive Immunochemical Determination of Ribonuclease Using Transition Metal Ions and the Effect of Catalytic Hydrogen Release by Yu. I. Dykhal; E. P. Medyantseva; N. R. Murtazina; G. R. Safina; G. K. Budnikov; N. V. Kalacheva (pp. 553-558).
A noncompetitive variant of immunochemical ribonuclease (RNase) determination has been developed, involving the use of Co(II) as a label. A variety of approaches to labeling the immunological reagent with the metal have been assessed. In the variant proposed, catalytic hydrogen release is used as a means of detecting the label, the amount of which is proportional to the RNase concentration. Conditions making it possible to record catalytic hydrogen release currents have been determined. In the presence of RNase, the electrocatalytic effect is maximum at a concentration of Co(II) in ammoniac buffer equal to 2 × 10–4 M (pH 10.0). The dependence is linear in the RNase concentration range 2000–4 ng/ml (threshold concentration, 2 ng/ml).
Kinetic Characteristics of Protein Hydrolysis during the Process of Induced Autolysis of the Biomass of Saccharomyces cerevisiae by T. L. Babayan; V. K. Latov (pp. 559-563).
The kinetics of the initial stages of autolysis of the yeast Saccharomyces cerevisiae was studied and the following kinetic parameters were determined: induction period, steady-state rate of the enzyme-induced effect, and steady-state concentration of intermediate products. It was shown that appropriate inducers were able to cause a more than fourfold increase in the rate of reactions catalyzed by proteinases and an almost tenfold increase in the concentration of intermediate peptides. The mean length of the peptide molecules formed in the process was determined and dependence of this value on the degree of hydrolysis was demonstrated.
Isolation and Characterization of a Cellobiose Dehydrogenase Formed by a Nonsporulating Mycelial Fungus INBI 2-26(-) by K. N. Karapetyan; S. N. Yachkova; L. G. Vasil'chenko; M. N. Borzykh; M. L. Rabinovich (pp. 564-572).
A nonsporulating fungus isolated from dioxin-containing tropical soils forms cellobiose dehydrogenase when grown in media supplemented by a source of cellulose. The enzyme purified to homogeneity by SDS-PAGE (yield, 43%) had an Mr of 95 kDa; its pH optimum was in the range 5.5–7.0; more than 50% activity was retained at pH 4.0–8.0 (citrate–phosphate buffer). The absorption spectrum of the enzyme in the visible range had the characteristic appearance of flavocytochrome proteins. Cellobiose dehydrogenase oxidized cellobiose and lactose (the respective K M values at pH 6.0 equaled 4.5 ± 1.5 and 56 μM) in the presence of dichlorophenolindophenol (K M,app = 15 ± 3 μM at pH 6.0) taken as an electron acceptor. Other sugars were barely if at all oxidized by the enzyme. Neither ethyl-β-D-cellobioside, heptobiose, nor chitotriose inhibited the enzymatic oxidation of lactose, even under the conditions of 100-fold molar excess. The enzyme was weakly inhibited by sodium azide dichlorophenolindophenol reduction and exhibited an affinity for amorphous cellulose. At 55°C and pH 6.0 (optimum stability), time to half-maximum inactivation equaled 99 min. The enzyme reduced by cellobiose was more stable than the nonreduced form. Conversely, the presence of an oxidizer (dichlorophenolindophenol) decreased the stability eight times at pH 6.0. In addition, the enzyme acted as a potent reducer of the one-electron acceptor cytochrome c 3+ (K M app = 15 μM at pH 6.0).
Biosynthesis of Hydrolytic Enzymes during Cocultivation of Macro- and Micromycetes by S. P. Vinogradova; S. N. Kushnir (pp. 573-575).
Effects of cocultivation of higher basidiomycetes and zygomycetes on biosynthesis of cellulases, amylases, and proteases were studied. Four optimal pairs of cultures of fungi were selected. Of these, three pairs belonged to higher fungi and one pair was constituted by fungi of distinct ecological groups, a macromycete and a micromycete. The activities of amylase and protease were 1.5–2 times higher and the activity of cellulase was lower during the growth of associations of higher fungi. The mixed association of the macromycete Schizophyllum commune and the micromycete Mucor sp. was the most active producer of hydrolytic enzymes. During the growth of this mixed association, increases of 4 and 1.5 times were observed in the activity of endoglucanase and protease, respectively, paralleled by stimulation of amylase formation.
Action of Cu2+ on Bacillus thuringiensis Growth Investigated by Microcalorimetry by Yao Jun; Liu Yi; Tuo Yong; Liu Jianben; Chen Xiong; Zhou Qin; Dong Jiaxin; Qu Songsheng; Yu Ziniu (pp. 576-580).
By using an LKB-2277 Bioactivity Monitor, ampoule mode, the heat output of Bacillus thuringiensis growth metabolism is determined at 28°C and the effect of Cu2+ on B. thuringiensis growth is studied. Copper is regarded as an essential trace element for life. Its deficiency may be the cause of diseases. Cu2+ at different concentrations has different effects on B. thuringiensis growth metabolism: a low concentration (0–30 μg/ml) of Cu2+ can promote the growth of B. thuringiensis, a high concentration (40–120 μg/ml) can inhibit growth of the bacteria, and a concentration of Cu2+ of up to 130 μg/ml completely inhibits B. thuringiensis growth.
Isolation of Hydrocarbon-Oxidizing Psychroactive Bacteria from Oil-Polluted Soils by D. V. Khomyakova; I. V. Botvinko; A. I. Netrusov (pp. 581-584).
Microorganisms growing on a mineral medium with crude oil and its light fractions as the only source of carbon and energy have been isolated from samples of oil-polluted soils collected in the Usa district (Komi Republic, Russia). Hydrocarbon-oxidizing psychroactive bacteria of the genus Cytophaga, which are clearly capable of consuming crude oil hydrocarbons, have been identified for the first time. A method for cultivating microorganisms on porous plastic is proposed.
Degradation of bis-(2-Ethylhexyl)phthalate by Microorganisms of the Water and Bottom Sediments of the Selenga River and Lake Baikal under Experimental Conditions by I. N. Azarova; V. V. Parfenova; G. I. Baram; I. A. Terkina; O. N. Pavlova; M. Yu. Suslova (pp. 585-589).
Degradation of bis-(2-ethylhexyl)phthalate (BEHP) by microbial associations of the water and bottom sediments of the Selenga River and Lake Baikal and by pure cultures of microbial species belonging to various taxa isolated from the sediments under discussion is studied. It is shown that intense biological degradation occurs in both water and sediments. The degrees of conversion in closed experimental systems on minimal media are 46 and 24%, respectively. The most active of the organisms studied is a Micromironospora actinomycete. It degraded BEHP by 36% of its initial concentration. Spore-forming bacteria and microorganisms of the genus Pseudomonas were less active (17–23% and 7–11%).
Biochemical Characterization of Aeromonad Strains Differing in Pathogenicity by V. V. Bogdan; L. P. Smirnov; N. N. Nemova; M. Yu. Krupnova (pp. 590-594).
A virulent strain of motile aeromonad (77-18) differed from an avirulent strain (78-16) in the contents of lipids and phospholipids and odd-numbered fatty acids, activity of hydrolytic enzymes, and amount of proteins with molecular weights of 47–56 kDa. It is assumed that proteins with molecular weights of 47–56 kDa, proteolytic enzymes active within a wide pH range, and odd fatty acids may act as pathogenicity factors. Each of these compounds or their combination determines a certain stage of infection.
Inhibitory Effect of an Antimicrobial Preparation from Lipids of Marine Fishes on Tissue and Microbial Enzymes by T. A. Davletshina; L. V. Shul'gina; L. Yu. Lazhentseva; Yu. G. Blinov; T. N. Pivnenko (pp. 595-598).
A new food preservative from marine fish lipids, was obtained possessing pronounced activity in relation to bacteria and microscopic fungi. The effects of this preparation on enzymes of microorganisms and muscle tissue of marine hydrobionts were studied. In vitro, the preparation irreversibly inhibited acid and alkaline proteases and proteolytic and lipolytic enzymes of microorganisms and reduced enzyme activity in fish muscle tissue. The inhibitory effect of this preparation on enzymes contributes to stabilization of hydrolytic processes in meat of hydrobionts and suppresses microorganism growth during storage.
Studies of the Efficacy of Alfalfa and Reed in the Phytoremediation of Hydrocarbon-Polluted Soil by A. Yu. Muratova; O. V. Turkovskaya; T. Hübner; P. Kuschk (pp. 599-605).
The efficacy of plants as means of decontaminating hydrocarbon-polluted soil has been studied. Ditch reed (Phragmites australis) and alfalfa (Medicago sativa) markedly intensified processes of pollutant destruction, the effect being particularly pronounced in the case of polycyclic aromatic hydrocarbons. Comparative analysis of microflora in soils (including those devoid of plants and rhizosphere) demonstrated that, in addition to preventing a pollutant-induced decrease in the amount of heterotrophic microorganisms, the plants stimulated their development, significantly increasing the population of degraders. Effects of plants on major physiological groups of soil microorganisms under conditions of pollution were ambiguous. The rhizosphere microbial consortium of alfalfa was less susceptible to effects of pollutants than that of reed.
Photosynthetic Pigments of Tomato Plants under Conditions of Biotic Stress and Effects of Furostanol Glycosides by I. S. Vasil'eva; S. A. Vanyushkin; S. V. Zinov'eva; Zh. V. Udalova; Yu. V. Bolychevtseva; V. A. Paseshnichenko (pp. 606-612).
The adaptogenic effect of furostanol glycosides (FG) on biosynthesis of photosynthetic pigments in tomato plants (Lycopersicon esculentum Mill.) was studied under conditions of biotic stress caused by root-knot nematode (Meloidogyne incognita Kofoid et White). Treatment of plants with 5 × 10–4 M FG was accompanied by an increase in the rate of biosynthesis of pigments (particularly, chlorophyll b and carotenoids), which was observed against the background of a decrease in the relative contribution of β-carotene and an increase in the relative contribution of pigments of the violaxanthin cycle (VXC) to the overall pool of carotenoids. It was suggested that FG stimulated phytoimmunity by shifting metabolism of carotenoids toward enhanced biosynthesis of VXC pigments. These pigments play a protective role and facilitate stabilization of the photosynthetic apparatus, which is particularly important under stress conditions.
Regulation of Potato Immune Responses by Laminarin by N. I. Vasyukova; G. I. Chalenko; T. A. Valueva; N. G. Gerasimova; Ya. S. Panina; O. L. Ozeretskovskaya (pp. 613-617).
Laminarin blocks potato immune responses by inhibiting the reaction of oversensitivity, formation of phytoalexins, wound repair, and the activity of proteinase inhibitors. It was found that laminarin exhibits antielicitor activity. Addition of salicylic acid to laminarin enhances its immunosuppressing effect, which becomes systemic.
Effect of the Composition of Polysaccharides in Gelatinized Cornstarch on Alcohol Absorption by T. A. Misharina; A. L. Samusenko; M. A. Kalinchenko (pp. 618-622).
Sorption of alcohols in aqueous suspensions of gelatinized cornstarches with various contents of amylose was studied by capillary gas chromatography. Alcohol sorption depended primarily on the structure of alcohols, rather than on the composition of polysaccharides. No correlation was found between the efficiency of sorption and amylose content in starch. The amount of substances sorbed by starches depended linearly on their initial concentration in the gel. Normal and high-amylose starches sorbed alcohols to a similar degree. However, increasing the length of alkyl substituents improved sorption of alcohols. Amylopectin starch differed in high affinity for small molecules and low sensitivity to the structure and hydrophobicity of alcohols.