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991.
Jan Douda Karel Boublík Michal Slezák Idoia Biurrun Josef Nociar Alena Havrdová Jana Doudová Svetlana Aćić Henry Brisse Jörg Brunet Milan Chytrý Hugues Claessens János Csiky Yakiv Didukh Panayotis Dimopoulos Stefan Dullinger Úna FitzPatrick Antoine Guisan Peter J. Horchler Richard Hrivnák Ute Jandt Zygmunt Kącki Balázs Kevey Flavia Landucci Hugues Lecomte Jonathan Lenoir Jaanus Paal David Paternoster Harald Pauli Remigiusz Pielech John S. Rodwell Bart Roelandt Jens‐Christian Svenning Jozef Šibík Urban Šilc Željko Škvorc Ioannis Tsiripidis Rossen T. Tzonev Thomas Wohlgemuth Niklaus E. Zimmermann 《应用植被学》2016,19(1):147-163
992.
Konstantin M. Boyko Tatiana N. Stekhanova Alena Yu. Nikolaeva Andrey V. Mardanov Andrey L. Rakitin Nikolai V. Ravin Ekaterina Yu. Bezsudnova Vladimir O. Popov 《Extremophiles : life under extreme conditions》2016,20(2):215-225
The gene TUZN1299 from the genome of the hyperthermophilic archaeon Thermoproteus uzoniensis encoding a new 32.8 kDa branched-chain amino acid aminotransferase (BCAT) was expressed in Escherichia coli. The recombinant protein TUZN1299 was purified to homogeneity in the PLP-bound form. TUZN1299 was active towards branched-chain amino acids (l-Val, l-Leu, l-Ile) and showed low but detectable activity toward (R)-alpha-methylbenzylamine. The enzyme exhibits high-temperature optimum, thermal stability, and tolerance to organic solvents. The structure of an archaeal BCAT called TUZN1299 was solved for the first time (at 2.0 Å resolution). TUZN1299 has a typical BCAT type IV fold, and the organization of its active site is similar to that of bacterial BCATs. However, there are some differences in the amino acid composition of the active site. 相似文献
993.
N. G. Loiko M. A. Krasnova T. V. Pichugina A. I. Grinevich V. I. Ganina A. N. Kozlova Yu. A. Nikolaev V. F. Gal’chenko G. I. El’-Registan 《Microbiology》2014,83(3):195-204
Effect of the antibiotics kanamycin and ampicillin on the growth and phase variation of the populations of four strains of lactic acid bacteria (Lactobacillus sp. M76AT, L. casei MB, Enterococcus faecium M, and E. faecium M3185) was studied. The presence of antibiotics in the medium resulted in a dose-dependent decrease in viable cell numbers and in partial or complete substitution of the dominant S variant with the minor Sm and Sb variants. The variants differed in colony morphology, as well as in some physiological, biochemical, biotechnological, and probiotic characteristics. The Sm type variants of all strains exhibited the highest resistance to antibiotics. High production of exopolysaccharides was found in Sb variants of lactobacilli and in S variants of enterococci. The highest antibacterial activity was found in Sm variants of lactobacilli, especially in Lactobacillus sp. M76AT. The latter is biotechnologically the most promising strain, since all variants fermented milk yielding the products with uniformly pronounced functional and organoleptic properties. These patterns are of importance for the understanding of the mechanisms of antibiotic resistance and for selection of the variants with desired properties, as well as for quality control of the lactic acid bacteria starter cultures. 相似文献
994.
Mrácek T Pecinová A Vrbacký M Drahota Z Houstek J 《Archives of biochemistry and biophysics》2009,481(1):30-36
We investigated hydrogen peroxide production in mitochondria with low (liver, heart, brain) and high (brown adipose tissue, BAT) content of glycerophosphate dehydrogenase (mGPDH). ROS production at state 4 due to electron backflow from mGPDH was low, but after inhibition of electron transport with antimycin A high rates of mGPDH-dependent ROS production were observed in liver, heart and brain mitochondria. When this ROS production was related to activity of mGPDH, many-fold higher ROS production was found in contrast to succinate- (39-, 28-, 3-fold) or pyruvate plus malate-dependent ROS production (32-, 96-, 5-fold). This specific rate of mGPDH-dependent ROS production was also exceedingly higher (28-, 66-, 22-fold) compared to that in BAT. mGPDH-dependent ROS production was localized to the dehydrogenase + CoQ and complex III, the latter being the highest in all mitochondria but BAT. Our results demonstrate high efficiency of mGPDH-dependent ROS production in mammalian mitochondria with a low content of mGPDH and suggest its endogenous inhibition in BAT. 相似文献
995.
N. A. Ushakova E. S. Brodskii A. A. Kozlova A. V. Nifatov 《Applied Biochemistry and Microbiology》2009,45(1):61-67
Solid-phase growth of Bacillus subtilis 8130 on cellulose-rich plant substrates (presscakes or pulp) under hypoxic conditions was accompanied by cellulose depolymerization, protein hydrolysis, and degradation of other plant components, including some processes of mixed-type carbohydrate fermentation. The bacterial fermentation yielded propionic, butyric, hexanoic acids and butyric acid derivatives. The bacterial metabolism and fermentation degree can be characterized by the proportions of fatty acids in the reaction mixture. The product of sea buckthorn cake fermentation has a good sorption quality. 相似文献
996.
A. S. Petrovskii D. G. Deryabin N. G. Loiko N. A. Mikhailenko T. G. Kobzeva P. A. Kanaev Yu. A. Nikolaev Yu. F. Krupyanskii A. N. Kozlova G. I. El’-Registan 《Microbiology》2009,78(2):144-153
In our study, we investigated the capacity of alkylhydroxybenzenes (AHB), which are microbial anabiosis autoinducers, for alteration of the enzymatic activity of the hen egg-white lysozyme, as well as the efficiency of hydrolysis of specific (peptidoglycan) and nonspecific (chitin) substrates catalyzed by lysozyme. AHB homologues (C7-AHB and C12-AHB), which differ in their hydrophobicity and effects in their interaction with lysozyme, were used as modifying agents. C7-AHB stimulated enzymatic activity within the whole range of concentrations used (10?7?10?3 M). More hydrophobic C12-AHB exhibited this ability only at low concentrations and inhibited fermentative activity at high concentrations, acting as a mixed-type inhibitor. Both AHB homologues caused changes in the hydrophobicity of lysozyme molecules. An increase in the affinity level between the C7-AHB-modified enzyme and the nonspecific substrate (colloidal chitin or cell wall polymers of Saccharomyces sp.) was observed, which manifested itself in the enhancement of the hydrolysis rate by 200–500% (as compared to the native enzyme). A significant effect on the efficiency of the lysozyme-catalyzed modifications of the substrate (peptidoglycan, colloidal chitin) structure as a result of its complexation with AHB was demonstrated. A stabilizing effect of C7-AHB and C12-AHB was revealed, which ensured a high level of activity of the AHB-modified enzyme (as compared to the control) after heat treatment (functional stability), as well as at nonoptimal temperatures of catalysis (operational stability). The biological significance of lysozyme modification with AHB and the practical aspects of its application are discussed. 相似文献
997.
David Kub
Alena ejkov Jan Mask Vladimír Jirk Marielle Lemaire Estelle Gallienne Jean Bolte Radek Stloukal Ludmila Martínkov 《Journal of Molecular Catalysis .B, Enzymatic》2006,39(1-4):59-61
Whole cells of Rhodococcus equi A4, a producer of nitrile hydratase and amidase activities, were immobilized in lens-shaped hydrogel particles, LentiKats®. The immobilized biocatalyst was applied to the biotransformation of benzonitrile, 3-cyanopyridine, (R,S)-3-hydroxy-2-methylenebutanenitrile and (R,S)-3-hydroxy-2-methylene-3-phenylpropanenitrile. The stability of the nitrile hydratase during the repeated use of the biocatalyst was dependent on the type of the substrate. The enzyme was most stable during the transformation of (R,S)-3-hydroxy-2-methylenebutanenitrile. No significant loss of the amidase activity was observed within the course of the biocatalytic reaction. 相似文献
998.
Zdrazilová P Stĕpánková S Komersová A Vránová M Komers K Cegan A 《Zeitschrift für Naturforschung. C, Journal of biosciences》2006,61(7-8):611-617
Kinetics of hydrolysis of acetylcholine and acetylthiocholine by two types of acetylcholinesterase and butyrylcholinesterase inhibited by 13 new inhibitors (5 carbamates and 8 carbazates--hydrazinium derivatives) was measured in vitro in a batch reactor at 25 degrees C, pH 8, ionic strength 0.11 M and enzyme activity 3.5 U by four nondependent analytical methods. Sevin, rivastigmin (Exelon) and galantamin (Reminyl) served as comparative inhibiting standards. Kinetics of hydrolyses inhibited by all studied carbamates, sevin, carbazates (with exceptions) and rivastigmin (with exceptions) can be simulated by the competitive inhibition model with irreversible reaction between enzyme and inhibitor. Galantamin does not fulfil this model. In positive simulations, the value of inhibition (carbamoylation) rate constant k3 was calculated, describing the reaction velocity between the given enzyme and inhibitor. Physiologically important hydrolyses of acetylcholine catalyzed by acetylcholinesterase from electric eel or bovine erythrocytes and butyrylcholinesterase from horse plasma can be most quickly inhibited by carbamoylation of the mentioned enzymes by the 3-N,N-diethylaminophenyl-N'-(1-alkyl) carbamates 4 and 5. Probably this is due to a long enough hydrocarbon aliphatic substituent (hexyl and octyl) on the amidic nitrogen atom. The tested carbazates failed as inhibitors of cholinesterases. The regeneration ability of the inhibited enzymes was not measured. 相似文献
999.
Wilhelm J Fuksová H Schwippelová Z Vytásek R Pichová A 《BioFactors (Oxford, England)》2006,27(1-4):185-193
Free radicals are considered the most important cause of cellular ageing. We have investigated ageing process in the yeast Saccharomyces cerevisiae. We have compared the wild type strain with the mutant cells with constitutively active Ras oncogen, which generates increased amounts of free radicals. Increased generation of oxygen-derived free radicals resulted in the Ras mutant cells accumulation of lipofuscin-like pigments during ageing. Ageing wild type cells did not accumulate lipofuscin-like pigments. This is quite unique feature among known biological models. It may be caused by increased concentration of alpha tocopherol (the most prominent lipophilic antioxidant) in the wild type cells. In contrast, the Ras mutant cells contained decreased levels of alpha tocopherol even in the young cells. This observation indicates that the increased free radical generation can overwhelm the endogenous antioxidant system. We have documented the involvement of nitrogen-derived free radicals in the yeast metabolism. Protein nitrotyrosine, a marker of the reactive nitrogen species, has significantly increased in the senescent Ras mutant cells. The wild type cells contained basic level of nitrotyrosine corresponding to its concentration found in non-activated mammalian macrophages. 相似文献
1000.
Stadnikov AA Shevliuk NN Kozlova AN 《Zhurnal mikrobiologii, epidemiologii, i immunobiologii》2006,(4):46-49
Morphofunctional equivalents of the process of long-term intracellular prokaryotes--eukaryotes interaction were studied by light and electron microscopy. The mechanisms for adaptation, elaborated in the course of evolution of bacteria-host interaction, were analysed on the ultrastructural level. A concept on the role of hypothalamic nonapeptides, as factors of regulation of intracellular persistence and symbiosis of prokaryotes, is discussed. 相似文献