Search results for "CITRIC ACID"
showing 10 items of 111 documents
Genetic organization of the citCDEF locus and identification of mae and clyR genes from Leuconostoc mesenteroides.
1999
ABSTRACT In this paper, we describe two open reading frames coding for a NAD-dependent malic enzyme ( mae ) and a putative regulatory protein ( clyR ) found in the upstream region of citCDEFG of Leuconostoc mesenteroides subsp. cremoris 195. The transcriptional analysis of the citrate lyase locus revealed one polycistronic mRNA covering the mae and citCDEF genes. This transcript was detected only on RNA prepared from cells grown in the presence of citrate. Primer extension experiments suggest that clyR and the citrate lyase operon are expressed from a bidirectional A-T-rich promoter region located between mae and clyR.
Diacetyl and acetoin production from the co-metabolism of citrate and xylose by Leuconostoc mesenteroides subsp. mesenteroides.
1997
The co-metabolism of citrate plus xylose by Leuconostoc mesenteroides subsp. mesenteroides results in a growth stimulation, an increase in D-lactate and acetate production and repression of ethanol production. This correlated well with the levels of key enzymes involved. A partial repression of alcohol dehydrogenase and a marked stimulation of acetate kinase were observed. High citrate bioconversion yields in diacetyl plus acetoin were obtained at pH 5.2 in batch (11.5%) or in chemostat (up to 17.4%) culture. In contrast, no diacetyl or acetoin was detected in citrate plus glucose fermentation.
A descriptive model for citrate utilization by Lactococcus lactis ssp lactis bv diacetylactis
1993
A model for the use of citrate by Lactococcus lactis ssp lactis bv diacetylactis CNRZ 125 is proposed. Citrate metabolism by this strain leads to the production of acetate, CO2 and C4 compounds (diacetyl, acetoin, 2,3-butylene glycol). The model furnishes correct simulations, consistent with published results on the pathways used and on lactose-citrate co-metabolism. Citric acid is incorporated independently of growth. The production of flavoring compounds is a complex process, depending on the rate of citrate utilization, on the proportion of pyruvate arising from citrate and which condenses to form α-acetolactate and CO2, on the rate of transformation of α-acetolactate to diacetyl and ace…
The quality of plasma collected by automated apheresis and of recovered plasma from leukodepleted whole blood.
2005
Background There exists a current lack of information about the composition of the different types of plasma. No direct comparisons between apheresis plasma (AP) and recovered plasma (RP) derived from in-line-filtered whole blood (WB) have been published to date. Study design and methods Sixty AP units, 100 RP units from in-line-filtered WB held for 3 hours at 20 degrees C between donation and freezing, and an additional 100 RP units held for 15 hours at 20 degrees C before freezing were analyzed for coagulation factors and inhibitors, total protein, immunoglobulin G (IgG), and hemostasis and proteolysis activation markers. The influence of twice freezing and thawing on clotting factors V, …
The importance of citrates in treatment and prophylaxis of calcium oxalate urinary stones
2017
About 10% of the people is the subject of an episode of kidney stones during their lifetime, about 70% of these people undergoes relapses. About 80% of the urinary stones contains calcium, of wich 80% is formed of calcium oxalate, in pure form or associated with calcium phosphate. Therefore we can saythat in most cases (about 65%) the urinary stones are composedof calcium oxalate. Use of supplements of potassium citrate and magnesium citrate can help in the prevention of kidney stones of calcium oxalate, but mostly they can be used in the days before a shockwaves lithotripsy treatment to make the stones more fragile to the effect of the shock waves. A case of successful treatment with magne…
Upgrading cytochrome P450 activity in HepG2 cells co-transfected with adenoviral vectors for drug hepatotoxicity assessment
2011
In a number of adverse drug reactions leading to hepatotoxicity, drug metabolism is thought to be involved by the generation of reactive metabolites from non-toxic drugs. The use of hepatoma cell lines, such as HepG2 cell line, for the evaluation of drug-induced hepatotoxicity is hampered by their low cytochrome P450 expression which makes impossible the study of the toxicity produced by bioactivable compounds. Genetically manipulated cells constitute promising tools for hepatotoxicity applications. HepG2 cells were simultaneously transfected with recombinant adenoviruses encoding CYP1A2, CYP2C9 and CYP3A4 to confer them drug-metabolic competence. Upgraded cells (Adv-HepG2) were highly able…
Decomposition of ammonium sulfate residue in a high solid/gas ratio suspension state with an industrial-scale reactor system (production line)
2015
Abstract Ammonium sulfate residue is a particulate solid and is produced during the manufacture of ammonium sulfate fertilizer. The residue used in this study contained a large portion of calcium carbonate, from which active lime (CaO) was recovered via thermal decomposition. We used a purpose-built device to decompose the residue in a semi-suspension state. We found that CaO had the highest activity when residue was decomposed at 850–900 °C. Our experiments indicated that ammonium sulfate residue should be decomposed in a suspension state to produce active CaO. Based on our laboratory test findings, an industrial-scale production line with a high solid/gas ratio in a suspension state was d…
Localization of Lactococcus lactis ssp lactis bv diacetylactis in alginate gel beads affects biomass density and synthesis of several enzymes involve…
1993
Lactococcus lactis ssp lactis bv diacetylactis, immobilized in calcium alginate beads, was grown in synthetic medium in a continuous flow reactor. Cell distribution inside the gel, as well as the activity of various enzymes, was measured after 30 h of operation. The included biomass tended to concentrate at the periphery of the bead along a section of radius about 100 μm long. ATPase activity was maximal in this zone. The activity of NADH oxidase, alcohol dehydrogenase, diacetyl reductase and acetoin reductase, which are repressed in the presence of citrate, were higher in the deeper zones than at the surface of the beads. This result shows that only the peripheral zone of the bead is respo…
Modeling of continuous Ph-stat stirred tank reactor withLactococcus lactisssp.lactisbv.diacetylactisimmobilized in calcium alginate gel beads
1995
A dynamic diffusion-reaction-growth model is proposed for the study of lactic fermentation, the bioconversion of citric acid, and cell release in an immobilized cell reactor [pH-stat continuous stirred tank-reactor (CSTR)]. The model correctly simulates the onset of fermentation and colonization of the gel, followed by the steady state. External diffusion is nonlimiting and internal diffusion is limited by high cell densities at the periphery of the gel beads. Lactose-citrate cometabolism in the gel is related to the distribution of active included biomass within the gel and to gradients of substrates (lactose, citrate) and products (lactate, pH) in the beads. The utilization of lactose is …
Specific interaction of citrate with bis(fluorophoric) bibrachial lariat aza-crown in comparison with the other components of the Krebs cycle
2006
Clares Garcia, M. Paz, M.Paz.Clares@uv.es ; Garcia-España Monsonis, Enrique, Enrique.Garcia-Es@uv.es ; Soriano Soto, Concepcion, Concepcion.Soriano@uv.es ; Tejero Toquero, Roberto, Roberto.Tejero@uv.es