Search results for "CITRIC ACID"
showing 10 items of 111 documents
Synthesis of WO3 nanorods through anodization in the presence of citric acid: Formation mechanism, properties and photoelectrocatalytic performance
2021
[EN] In this study, WO3 nanomds have been fabricated by simple anodization in the presence of different amounts of citric acid and at different anodization times. A comprehensive morphological, structural, electrochemical and photoelectrochemical characterization of different samples has been carried out. Moreover, a formation mechanism for WO3 nanorods has been proposed. Finally, these nanostructures have been proven to be excellent visible-light photoelectrocatalysts to remove persistent organic pollutants present in wastewaters, such as fenamiphos. Almost the 80% of this molecule was eliminated from the test solution after 180 min of irradiation, indicating the great potential of these W…
The Measurement of Enzyme Activities in the Resting Human Polymorphonuclear Leukocyte — Critical Estimate of a Method
1993
As a system for study, the isolated human polymorphonuclear leukocyte combines the advantages of a quasi-non-invasive preparation with a nearly complete complement of enzymes of carbohydrate and energy metabolism. However, small sample volumes and, in some cases, very low enzyme activities make high demands on sample processing, storage, and performance of continuous measurements, if the enzyme activities are to be measured with acceptable reproducibility. In the presented study several aspects of homogenization, storage, and continuous measurement were scrutinized, to identify critical steps and consider ways of optimizing the method. Polymorphonuclear leukocytes were separated from the bl…
Mutation of the oxaloacetate decarboxylase gene of Lactococcus lactis subsp. lactis impairs the growth during citrate metabolism
2007
; Aims: Citrate metabolism generates metabolic energy through the generation of a membrane potential and a pH gradient. The purpose of this work was to study the influence of oxaloacetate decarboxylase in citrate metabolism and intracellular pH maintenance in relation to acidic conditions. Methods and Results: A Lactococcus lactis oxaloacetate decarboxylase mutant [ILCitM (pFL3)] was constructed by double homologous recombination. During culture with citrate, and whatever the initial pH, the growth rate of the mutant was lower. In addition, the production of diacetyl and acetoin was altered in the mutant strain. However, our results indicated no relationship with a change in the maintenanc…
Zur Wirkung von Butazolidin im Intermedi�rstoffwechsel
1956
Butazolidin (Phenylbutazone) inhibits the oxidative decarboxylation of pyruvate and α-ketoglutarate in a final concentration of 10 mg-% (3,24 · 10−4 m). Data are presented suggesting that the β-ketothiolase is inhibited. The following enzymes or enzyme systems are not inhibited: The enzymes of the respiratory chain, the enzymes of the citric acid cycle with exception of α-ketoglutaric oxidase, the glycolysis of hexosediphosphate (slight inhibition), acetate thiokinase, sulfanilamid transacetylase, pyruvic decarboxylase from yeast, arginase, xanthine oxidase, and D-amino acid oxidase.
Effects of different infant formula components on calcium dialysability
1999
The in vitro methods proposed for estimating calcium bioavailability can be useful in studying the effect of dietetic factors. The aim of our work was to study the possible influence of different infant formula components – calcium, phosphorus, lactose, citric acid, ascorbic acid and proteins – on calcium bioavailability, considering dialysability to be an estimate of bioavailability. The 1981 method of Miller et al. with slight modifications (concerted action no 10 – FLAIR project) was applied to 18 commercial infant formulas of six different types: adapted, follow-up, preterm, hydrolysates, lactose-free and soy-based. Significant positive linear correlations between the amount of calcium …
Influence of carboxylic acids on the stereospecific nicotinamide adenine dinucleotide-dependent and nicotinamide adenine dinucleotide-independent lac…
1971
Leuconostoc mesenteroides increased its lactic acid production from glucose threefold when malic acid was added to the culture. This increase resulted also in a reduction of the ratio of d -lactic acid to l -lactic acid (31.5 to 1.23). Addition of malic acid increased 6.5-fold the specific activity of nicotinamide adenine dinucleotide (NAD)-linked l -lactate dehydrogenase and increased 3.2-fold that of NAD-linked d -lactate dehydrogenase. The Michaelis constant ( K m ) for NAD of the NAD-linked l -lactate dehydrogenase increased with the addition of malate, but no change was observed in the K m values for the respective d -enzyme. The effect of carboxylic acids on the NAD-linked l -lactate…
Effects of indole-3-acetic acid on Sinorhizobium meliloti survival and on symbiotic nitrogen fixation and stem dry weight production
2009
We evaluated the effects of the main auxin phytohormone, indole-3-acetic acid (IAA), on the central metabolism of Sinorhizobium meliloti strain 1021. We either treated the Sinorhizobium meliloti 1021 strain with 0.5 mM IAA (1021+) or use a derivative, RD64, of the same strain harbouring a pathway for IAA biosynthesis converting tryptophan into IAA via indoleacetamide. We assayed the activity of key enzymes in the major energy-yielding pathways (Entner-Doudoroff, Embden-Meyerhof-Parnas, pentose phosphate, glyoxylate bypass and tricarboxylic acid cycle). We found that activity of two main regulative tricarboxylic acid (TCA) cycle enzymes was increased. Citrate synthase (CS) activity, as compa…
Fumarate dependent protein composition under aerobic and anaerobic growth conditions in Escherichia coli
2020
Abstract In the absence of sugars, C4-dicarboxylates (C4DC) like fumarate represent important substrates for growth of Escherichia coli. Aerobically, C4DCs are oxidized to CO2 whereas anaerobically, C4DCs are used for fumarate respiration. In order to determine the impact of fumarate under aerobic and anaerobic conditions, proteomes of E. coli W3110 grown aerobically or anaerobically with fumarate and/or the non-C4DC substrate glycerol were comparatively profiled by nanoLC-MS/MS. Membrane enrichment allowed sensitive detection of membrane proteins. A total of 1657 proteins of which 646 and 374 were assigned to the cytosol or membrane, respectively, were covered. Presence of fumarate trigger…
Adaptative biochemical pathways and regulatory networks in Klebsiella oxytoca BAS-10 producing a biotechnologically relevant exopolysaccharide during…
2012
Abstract Background A bacterial strain previously isolated from pyrite mine drainage and named BAS-10 was tentatively identified as Klebsiella oxytoca. Unlikely other enterobacteria, BAS-10 is able to grow on Fe(III)-citrate as sole carbon and energy source, yielding acetic acid and CO2 coupled with Fe(III) reduction to Fe(II) and showing unusual physiological characteristics. In fact, under this growth condition, BAS-10 produces an exopolysaccharide (EPS) having a high rhamnose content and metal-binding properties, whose biotechnological applications were proven as very relevant. Results Further phylogenetic analysis, based on 16S rDNA sequence, definitively confirmed that BAS-10 belongs t…
Factors that influence the quality of metabolomics data in in vitro cell toxicity studies: a systematic survey
2021
Abstract REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) is a global strategy and regulation policy of the EU that aims to improve the protection of human health and the environment through the better and earlier identification of the intrinsic properties of chemical substances. It entered into force on 1st June 2007 (EC 1907/2006). REACH and EU policies plead for the use of robust high-throughput "omic" techniques for the in vitro investigation of the toxicity of chemicals that can provide an estimation of their hazards as well as information regarding the underlying mechanisms of toxicity. In agreement with the 3R’s principles, cultured cells are nowadays wide…