Metabolites

The focus of this thesis was to study the chemotaxonomic relationship of selected southern Australian marine brown algae of the genera Cystophora and Sargassum. Consequently, this resulted in the isolation and structure elucidation of six new terpenoids from two southern Australian marine brown algae Cystophora moniliformis and Sargassum fallax together with 10 previously reported natural products. As a result of the re-isolation of these known secondary metabolites, updated and complete structural characterisation data could be provided for the first time for 7 of these compounds.

132p runthenight07 01-03-2023 8 3   Download

The thesis investigates the growth promoting effects of plant growth promoting bacteria (PGPB) in chickpea and wheat. Three main topics covered are: 1) Isolating local Plant Growth Promoting Bacteria; 2) Screening and characterization of isolates; 3) Assessment and identification of the selected strains.

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Thesis aims: Isolation and screening for Vietnam antimicrobial marine-derived actinobacteria strains. Isolation and structure elucidation of compounds from 2 promising isolated actinobacteria strains. Determination the antimicrobial activities of isolated compounds.

26p extraenglish 24-05-2021 28 4   Download

The objectives of the thesis: Study on chemical constituents of three Antidesma species including A. acidum, A. ghaesembilla, and A. hainanensis growing in Vietnam; evaluation of biological activities of isolated metabolites to find potential compounds.

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Isolation and screening for Vietnam antimicrobial marine-derived actinobacteria strains; isolation and structure elucidation of compounds from 2 promising isolated actinobacteria strains; determination the antimicrobial activities of isolated compounds.

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Obtaining of secondary metabolites from marine fungi isolated in the Central Vietnam and identifying some biological activities (antibiotimicrobial, cytotoxic, antioxidant, neuroprotective activities) of obtained individual compounds.

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An analytical procedure for the analysis of carotenoids in marine sediments rich in organic matter has been developed. Analysis of these compounds is difficult; the application of methods used by other authors required optimization for the samples studied here.

14p tocectocec 25-05-2020 27 1   Download

Polyphosphate polymer (polyP) plays a very important role in every living cell. Synthesis of this linear polymer of phosphate (Pi) residues is catalyzed by the polyphosphate kinase (PPK) enzyme.

16p nutifooddau 27-01-2019 17 2   Download

Modelling of the fluxes in central metabolism can be performed by combining labelling experiments with metabolite balancing. Using this approach, multiple samples from a cultivation of Saccharomyces cerevisiae in metabolic and isotopic steady state were analysed, and the metabolic fluxes in central metabolism were estimated. In the various samples, the estimates of the central metabolic pathways, the tricarboxylic acid cycle, the oxidative pentose phosphate pathway and the anaplerotic pathway, showed an unprecedented reproducibility....

6p system191 01-06-2013 41 2   Download

Glyoxal is a key compound involved in glyoxal oxidase (GLOX)-dependent production of glyoxylate, oxalate and H2O2 by lignin-degrading basidiomycetes. In this paper, we report that glyoxal was produced from a metabolite of ligninolytic fungi, linoleic acid, by manganese peroxidase (MnP)-dependent lipid peroxidation. In the absence of the parent substrate of linoleic acid, the dialdehyde was oxidized by MnP and Mn(III) chelate to start free radical reactions with emission of chemiluminescence at 700– 710 nm. ...

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Metabolite channelling, the process in which consecutive enzymes have confined substrate transfer in metabolic pathways, has been proposed as a biochemical mechanism that has evolved because it enhances catalytic rates and protects unstable intermediates. Results from experiments on the synthesis of radioactive urea [Cheung, C., Cohen, N.S. & Raijman, L (1989)J. Biol. Chem.264, 4038–4044] have been interpreted as implying channelling of arginine between argininosuccinate lyase and arginase in permeabi-lized hepatocytes. ...

9p tumor12 20-04-2013 35 1   Download

All higher organisms divide major biochemical steps into different cellular compartments and often use tissue-specific division of metabolism for the same purpose.Such spatial resolution is accompanied with temporal changes of meta-bolite synthesis in response to environmental stimuli or developmental needs.Although analyses of primary and secondary gene products, i.e. transcripts, proteins, and metabolites, regularly do not cope with this spatial and temporal resolution, these gene products are often observed to be highly coregulated forming complex networks....

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The currently applied reaction structure in stoichiometric flux balance mod-els for the nonoxidative branch of the pentose phosphate pathway is not in accordance with the established ping-pong kinetic mechanism of the enzymes transketolase (EC 2.2.1.1) and transaldolase (EC 2.2.1.2). Based upon the ping-pong mechanism, the traditional reactions of the nonoxida-tive branch of the pentose phosphate pathway are replaced by metabolite specific, reversible, glycolaldehyde moiety (C2 ) and dihydroxyacetone moi-ety (C3) fragments producing and consuming half-reactions. ...

13p fptmusic 12-04-2013 42 3   Download

One of the most drastic post-translational modification of proteins in eu-karyotic cells is poly(ADP-ribosyl)ation, catalysed by a family enzymes termed poly(ADP-ribose) polymerases (PARPs). In the human genome, 18 different genes have been identified that all encode PARP family members.

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The Sir2 family of histone⁄protein deacetylases (sirtuins) is comprised of homologues found across all kingdoms of life. These enzymes catalyse a unique reaction in which NAD + and acetylated substrate are converted into deacetylated product, nicotinamide, and a novel metabolite O-acetyl ADP-ribose. Although the catalytic mechanism is well conserved across Sir2 family members, sirtuins display differential specificity toward acetyl-ated substrates, which translates into an expanding range of physiological functions. ...

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Modelling of biochemical systems usually focuses on certain pathways, while the concentrations of so-called external metabolites are considered fixed. This approximation ignores feedback loops mediated by the environ-ment, that is, via external metabolites and reactions. To achieve a more realistic, dynamic description that is still numerically efficient, we propose a new methodology: the basic idea is to describe the environment by a lin-ear effective model of adjustable dimensionality.

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Arachidonic acid and its lypoxygenated metabolites play a fundamental role in the hormonal regulation of steroidogenesis. Reduction in the expres-sion of the mitochondrial acyl-CoA thioesterase (MTE-I) by antisense or small interfering RNA (siRNA) and of the arachidonic acid-preferring acyl-CoA synthetase (ACS4) by siRNA produced a marked reduction in steroid output of cAMP-stimulated Leydig cells.

11p awards 06-04-2013 39 4   Download

New technologies enable acquisition of large data-sets containing genomic, proteomic and metabolic information that describe the state of a cell. These data-sets call for systematic methods enabling relevant information about the inner workings of the cell to be extracted. One important issue at hand is the understanding of the functional interactions between genes, proteins and metabolites.

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Dehydroepiandrosterone (DHEA), a steroid hormone, modified the proli-feration of human umbilical vein endothelial cells in a dose-dependent manner. Its inactive sulfate ester (DHEA-S) and two of its metabolites – estradiol and testosterone – had no inhibitory effect at physiological concentrations. Antiproliferation was associated with arrest in the G1 phase of the cell cycle, but not with cell death, as evaluated by cleavage of poly(ADP-ribose) polymerase and exposure of phosphatidylserine. ...

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GE23077, a novel microbial metabolite recently isolated from Actinomadurasp. culture media, is a potent and selective inhibitor of bacterial RNApolymerase (RNAP). It inhibitsGram-positive (Bacillus subtilis) andGram-negative (Escherichia coli)RNAPs with IC50 values (i.e. the concen-tration at which the enzyme activity is inhibited by 50%) in the 10 )8 Mrange, whereas it is not active onE. coliDNA polymerase or on eukaryotic (wheat germ) RNAP II (IC50 values10 )4 Min both cases).

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