Search results for "REDUCTASE"
showing 10 items of 798 documents
The Effect of Light on the Growth of Pea Plants and the Subsequent Influence in Shikimate Oxidoreductase (EC 1.1.1.25) Activity
1981
Summary Pea plants were cultured in white light, red and far red light, and in the dark during a period of three weeks. At several states of development we investigated the activity of the enzyme shikimate oxidoreductase, the amount of fresh and dry matter, and the contents of protein in stem, leaves, cotyledons, and roots. The enzyme activity was found to be distributed organ-specifically and uninfluenced by the phytochrome system, but it was significantly depressed in plants grown in the dark compared to plants grown in white light. Enzyme activity occurred also in non photosynthetic plants. Regarding the different light conditions the activity of shikimate oxidoreductase was found to cor…
Target Analogue Imprinted Polymers with Affinity for Folic Acid and Related Compounds
2001
Two approaches to synthesize molecularly imprinted polymers with affinity for folic acid and other substituted pteridines have been compared. In the first approach, the folic acid analogue methotrexate was used as template and functional monomers capable of generating selective binding sites were searched in a miniaturized screening system based on binding assessment in the batch mode. Highest selectivity was seen using 2-vinylpyridine as functional monomer, which was confirmed in the chromatographic mode for a batch synthesized on a gram scale. However, the retentivity and selectivity of this phase were insufficient for anticipated applications. In a second approach, using methacrylic acid…
Experimental evidence for proton motive force-dependent catalysis by the diheme-containing succinate:menaquinone oxidoreductase from the Gram-positiv…
2006
In Gram-positive bacteria and other prokaryotes containing succinate:menaquinone reductases, it has previously been shown that the succinate oxidase and succinate:menaquinone reductase activities are lost when the transmembrane electrochemical proton potential, Deltap, is abolished by the rupture of the bacteria or by the addition of a protonophore. It has been proposed that the endergonic reduction of menaquinone by succinate is driven by the electrochemical proton potential. Opposite sides of the cytoplasmic membrane were envisaged to be separately involved in the binding of protons upon the reduction of menaquinone and their release upon succinate oxidation, with the two reactions linked…
Effect of Ti(IY) on some indicators of physiological activity inCapsicum annuum, L.
1994
SummaryPaprika pepper (Capsicum annuum, L., cv. Negral) plants grown in a greenhouse were supplied Ti(IV) ascorbate through the roots or through leaves. Biomass production, peroxidase (donor: H2O, oxidoreductase; EC 1.11.1.7) activity, and malic acid, starch and chlorophyll concentrations were determined in different plant organs. It was observed that Ti increased the concentration of some of the metabolites studied and promoted both peroxidase activity and biomass production. The profitable effect of the Ti treatments could occur because they enhance the availability of other nutrients. This effect could be due to the low redox potential of the Ti+3/Ti+4 system that catalyzes the activity …
Succinate dehydrogenase functioning by a reverse redox loop mechanism and fumarate reductase in sulphate-reducing bacteria.
2006
Sulphate- or sulphur-reducing bacteria with known or draft genome sequences (Desulfovibrio vulgaris, Desulfovibrio desulfuricans G20, Desulfobacterium autotrophicum [draft], Desulfotalea psychrophila and Geobacter sulfurreducens) all contain sdhCAB or frdCAB gene clusters encoding succinate : quinone oxidoreductases. frdD or sdhD genes are missing. The presence and function of succinate dehydrogenase versus fumarate reductase was studied. Desulfovibrio desulfuricans (strain Essex 6) grew by fumarate respiration or by fumarate disproportionation, and contained fumarate reductase activity. Desulfovibrio vulgaris lacked fumarate respiration and contained succinate dehydrogenase activity. Succi…
Metabolic cross-talk between pathways of terpenoid backbone biosynthesis in spike lavender
2015
Abstract The metabolic cross-talk between the mevalonate (MVA) and the methylerythritol phosphate (MEP) pathways in developing spike lavender ( Lavandula latifolia Med) was analyzed using specific inhibitors and on the basis of 13 C-labeling experiments. The presence of mevinolin (MEV), an inhibitor of the MVA pathway, at concentrations higher than 0.5 μM significantly reduced plant development, but not the synthesis of chlorophylls and carotenoids. On the other hand, fosmidomycin (FSM), an inhibitor of the MEP pathway, at concentrations higher than 20 μM blocked the synthesis of chlorophyll, carotenoids and essential oils, and significantly reduced stem development. Notably, 1.2 mM MVA cou…
Über den Abbau von L-Äpfelsäure durch Hefen verschiedener Gattungen mit Malatenzym
1974
Summary (1) The aerobic assimilation of malic acid is not a character of certain yeast genera or species as was shown by testing more than 300 different strains. Single strains of the following-species were found to grow on malic acid as the only carbon source: Candida pulcherrima, C. utilis, C. mycoderma, Torulopsis famata, Pichia membranaefaciens, P. wickerhamii, Hansenula capsulata, Trigonopsis variabilis , and Zygosaccharomyces chevalieri . (2) During fermentation C. pulcherrima and T. famata decompose up to 40% and C. utilis up to 80% of the L-malic acid that is present in the medium. (3) L-Malic acid is decomposed to CO 2 and the corresponding amounts of ethanol or pyruvate by cell fr…
Why Are Some Enzymes Dimers? Flexibility and Catalysis in Thermotoga maritima Dihydrofolate Reductase
2019
[Image: see text] Dihydrofolate reductase from Thermotoga maritima (TmDFHFR) is a dimeric thermophilic enzyme that catalyzes the hydride transfer from the cofactor NADPH to dihydrofolate less efficiently than other DHFR enzymes, such as the mesophilic analogue Escherichia coli DHFR (EcDHFR). Using QM/MM potentials, we show that the reduced catalytic efficiency of TmDHFR is most likely due to differences in the amino acid sequence that stabilize the M20 loop in an open conformation, which prevents the formation of some interactions in the transition state and increases the number of water molecules in the active site. However, dimerization provides two advantages to the thermophilic enzyme: …
Loss of Hyperconjugative Effects Drives Hydride Transfer during Dihydrofolate Reductase Catalysis
2019
Hydride transfer is widespread in nature and has an essential role in applied research. However, the mechanisms of how this transformation occurs in living organisms remain a matter of vigorous debate. Here, we examined dihydrofolate reductase (DHFR), an enzyme that catalyzes hydride from C4′ of NADPH to C6 of 7,8-dihydrofolate (H2F). Despite many investigations of the mechanism of this reaction, the contribution of polarization of the π-bond of H2F in driving hydride transfer remains unclear. H2F was stereospecifically labeled with deuterium β to the reacting center, and β-deuterium kinetic isotope effects were measured. Our experimental results combined with analysis derived from QM/MM si…
Early reductive stress followed by a late onset oxidative stress in acute myocardial infarction
2018
Introduction The idea that the cells might suffer from reductive rather than oxidative stress and that such stress may be relevant in pathophysiology has gained momentum. Aim We aimed at studying markers of oxidative stress and damage as well as the expression of antioxidant enzymes in a swine model of acute myocardial infarction (AMI) followed by reperfusion. Results and Discussion We found an increase in the GSH to GSSG ratio, a decrease in protein glutathionylation and a decrease in p38 MAPK phosphorylation after 90 minutes of ischaemia in heart samples. It was accompanied by an increase in the expression of Thioredoxin (TrX) and Peroxiredoxin (PrX) and a decrease in the expression of Gl…