Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.26 (invertase)
4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of pH (4.0, 4.5, or 5.0), temperature (T) (30, 35, or 40 degrees C) and dissolved oxygen (DO) (0.2, 2.0, 4.0,or 6.0 mg O2/L) on hexokinase and invertase formation by yeast were studied. The highest enzyme activities were attained at pH 4.0, DO = 4.0 mg O2/L, and T = 35 or 40 degrees C.
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PMID:Hexokinase production from S. cerevisiae. Culture conditions. 866 7

Oxygen-derived free radicals are known to be generated during ischemia/reperfusion injury and biomembranes are the prime target of these active species. In order to study the effect of in vivo generated free radicals on intestinal mucosal membrane, brush border membranes (BBM) were isolated from rat small intestine after subjecting to ischemia (I) and ischemia/reperfusion (I/R) injury and their lipid composition and marker enzyme activity were compared with BBM prepared from control animals. No significant alteration in the lipid composition of BBM was observed after I or I/R as compared to control. Membrane fluidity measurements showed that I/R increased the fluidity of BBM. Activity of alkaline phosphatase, one of the marker enzymes for BBM was reduced by I or I/R whereas activity of another BBM enzyme, sucrase was not altered. The decrease in alkaline phosphatase activity was more after reperfusion. In vitro fluidization of BBM using benzyl alcohol indicated that the inactivation of alkaline phosphatase was not due to change in fluidity. These results suggest that free radicals generated during I/R inactivate BBM alkaline phosphatase partially without altering the membrane lipid composition.
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PMID:Effect of ischemia/reperfusion on intestinal brush border membrane lipid composition, fluidity and enzyme activities. 874 34

Biosensors for the determination of glucose, sucrose and lactose were based on a Clark-type oxygen electrode covered with a membrane containing microbial cells. The glucose-sensing membrane was prepared with intact cells of Gluconobacter oxydans immobilized in gelatin cross-linked with glutardialdehyde. The disaccharide-sensing membranes were prepared by co-immobilization of G. oxydans with cells of Saccharomyces cerevisiae containing invertase for sucrose determination and with permeabilized cells of Kluyveromyces marxianus containing beta-galactosidase for lactose determination. The strain of G. oxydans that we used was able to oxidize both anomers of glucose at the same rate; there was therefore no need for mutarotase co-immobilization in disaccharide-sensing membranes. The sensitivity of glucose sensor was 50 nA/mM, the range of the calibration curve was 0-0.8 mM, the response time was 2 min, and the response after 1 week of storage was 62% of the initial response. The parameters of the disaccharide sensors were similar: linear range of calibration curve up to 4 mM, response time 5 min. The activities of the sensors after 1 week of storage at ambient temperature were in the range 50-65% of the initial activity.
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PMID:Microbial cell-based biosensor for sensing glucose, sucrose or lactose. 956 11

Sugar beet molasses is a natural resource for various products used in daily life, ranging from sucrose to amino acids for pharmaceutical industry. The separation of molasses into these high value components is performed on a large scale by ion exchange/exclusion chromatography. A biosensor system was set up for the "in time" analysis of serine and sucrose during molasses desugarisation. D-Serine was analysed with the multi-enzyme system D-serine dehydratase/lactic dehydrogenase and photometric detection of the NADH consumed. Sucrose was determined with invertase/mutarotase/glucose oxidase and the oxygen consumed was monitored amperometrically. An analysis could be performed within 2-5 min by directly injecting samples from the chromatographic process into the flow injection analysis system. The determination range for the sucrose analysis was 0-2.5 gl-1 and for the analysis of D-serine 0-0.5 gl-1. The standard deviation for the measurement of D-serine was 1.7%.
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PMID:Flow injection analysis system for the supervision of industrial chromatographic downstream processing in biotechnology. 988 58

Intestinal ischemia necessitates rapid re-establishment of blood flow to prevent irreversible anoxic tissue damage. However, reperfusion results in additional injury as a consequence of the generation of oxygen free radicals. To date, no clear-cut marker to differentiate between ischemia versus reperfusion injury is available. In this regard, previous studies from our laboratory utilizing a rat in vitro lipid peroxidation model demonstrated that the generation of free radicals resulted in the inactivation of only the intestinal brush border alkaline phosphatase enzyme, with no effect on other membrane-bound digestive enzymes. Current studies were designed to assess the possibility of alkaline phosphatase being a specific marker of the reperfusion injury in canine and human ex vivo ischemia/reperfusion models. Small bowels harvested from canines and organ donors were subjected to ischemia followed by reperfusion. Brush border membrane enzymes, alkaline phosphatase, sucrase, maltase, and gamma-glutamyl transpeptidase were assayed in mucosal extracts from intestines with ischemia versus reperfusion. In both experimental models, there was no change in any enzyme activity with warm ischemia alone. In contrast, alkaline phosphatase activity was significantly decreased in both the canine and human reperfusion models, with no change in specific activities of sucrase, maltase, and gamma-glutamyl transpeptidase. Our data indicate that the alkaline phosphatase enzyme activity may represent a potential marker of intestinal reperfusion injury and may permit quantitative assessments of therapeutic interventions in human intestinal reperfusion injury.
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PMID:Decrease in mucosal alkaline phosphatase: a potential marker of intestinal reperfusion injury. 1021 63

The yeast SUC2 gene, cloned on a multicopy plasmid pRB58, was used to study the effect of oxygen on the invertase expression of the recombinant Saccharomyces cerevisiae. Glucose repression was not the only factor affecting the invertase expression. The results obtained from the single-stage continuous cultures under microaerobic conditions showed that invertase expression was also strongly dependent on oxygen availability, and moving from anaerobic to aerobic conditions led to a five-fold increase in specific invertase activity. However, the cell yields under anaerobic conditions were quite low compared to those under aerobic conditions. These opposite effects of oxygen on cell growth and gene expression offer a strategy for maximizing invertase productivity by a two-stage continuous culture. The first stage was operated at a low level of glucose, around 100 mg/l, under aerobic conditions in order to obtain a high yield of yeast biomass, and the second stage maintained anaerobic conditions with residual glucose levels of 50 mg/l to derepress and fully induce invertase expression. The two-stage continuous culture resulted in a 2.5-fold increase in invertase productivity over that of a single-stage continuous culture.
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PMID:Effects of oxygen on invertase expression in continuous culture of recombinant Saccharomyces cerevisiae containing the SUC2 gene. 1022 82

We show here that invertase gene expression and the invertase-sucrose (Suc) synthase ratio decrease abruptly in response to low oxygen in maize root tips. In addition to aiding in the conservation of carbon and possibly ATP, this response has the potential to directly affect sugar signaling relative to carbon flux. Experiments were motivated by the potential for a reduced invertase/Suc synthase balance to alter the impact of respiratory and/or membrane carbon flux on sugar signaling. Maize (Zea mays L.) seedlings with 5-cm primary roots were exposed to anoxic (0% [v/v] O2), hypoxic (3% [v/v] O2), and aerobic conditions. Rapid repression of the Ivr1 and Ivr2 maize invertases by low oxygen was evident in root tips within 3 h at both the transcript and activity levels. The speed and extent of this response increased with the degree of oxygen deprivation and differed with genotypes. This decrease in expression also contrasted markedly to that of other genes for respiratory Suc metabolism, such as Suc synthases, which typically increased or remained constant. Although previous work showed that the contrasting effects of sugars on Suc synthase genes were reflected in their regulation by hypoxia and anoxia, the same was not observed for the differentially sugar-responsive invertases. Theoretically advantageous reductions in the invertase/Suc synthase balance thus resulted. However, where this response was extreme (an Oh43 inbred), total sucrolytic capacity dropped below an apparent minimum and root tip viability was reduced. Paradoxically, only Oh43 seedlings showed survival levels >80% (versus <50%) after extreme, long-term stress, suggesting a possible advantage for multiple means of reducing sink activity. Overall, our results demonstrate a rapid change in the regulation and balance of invertases and Suc synthases that could have an immediate impact on limiting the extent of Suc cleavage and reducing the extent of concomitant, hexose-based sugar signaling under low oxygen.
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PMID:Rapid repression of maize invertases by low oxygen. Invertase/sucrose synthase balance, sugar signaling potential, and seedling survival. 1051 52

Although oxidative stress has been implicated in development of gut pathologies, its role in intestinal fat transport has not been investigated. We assessed the effect of Fe(2+)-ascorbate-mediated lipid peroxidation on lipid synthesis, apolipoprotein biogenesis, and lipoprotein assembly and secretion. Incubation of postconfluent Caco-2 cells with iron(II)-ascorbate (0.2 mM/2 mM) in the apical compartment significantly promoted malondialdehyde formation without affecting sucrase activity, transepithelial resistance, DNA and protein content, and cell viability. However, addition of the oxygen radical-generating system reduced 1) [(14)C]oleic acid incorporation into cellular triglycerides (15%, P < 0.0002) and phospholipids (16%, P < 0.0005); 2) de novo synthesis of cellular apolipoprotein A-I (apo A-I) (18%, P < 0.05), apo A-IV (38%, P < 0.05), and apo B-48 (45%, P < 0.003) after [(35)S]methionine addition; and 3) production of chylomicrons (50%), VLDL (40%), LDL (37%), and HDL (30%) (all P < 0.0001). In contrast, increased total cellular cholesterol formation (96%, P < 0.0001), assayed by [(14)C]acetate incorporation, was noted, attributable to marked elevation (70%, P < 0.04) in activity of DL-3-hydroxy-3-methyl-glutaryl-CoA reductase, the rate-limiting enzyme in cholesterol synthesis. The ratio of Acyl-CoA to cholesterol acyltransferase, the esterifying cholesterol enzyme, remained unchanged. Fe(2+)-ascorbate-mediated lipid peroxidation modifies intracellular fat absorption and may decrease enterocyte efficiency in assembling and transporting lipids during gut inflammation.
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PMID:Iron-ascorbate alters the efficiency of Caco-2 cells to assemble and secrete lipoproteins. 1089 42

Plants lack specialised organs and circulatory systems, and oxygen can fall to low concentrations in metabolically active, dense or bulky tissues. In animals that tolerate hypoxia or anoxia, low oxygen triggers an adaptive inhibition of respiration and metabolic activity. Growing potato tubers were used to investigate whether an analogous response exists in plants. Oxygen concentrations fall below 5% in the centre of growing potato tubers. This is accompanied by a decrease of the adenylate energy status, and alterations of metabolites that are indicative of a decreased rate of glycolysis. The response to low oxygen was investigated in more detail by incubating tissue discs from growing tubers for 2 hours at a range of oxygen concentrations. When oxygen was decreased in the range between 21% and 4% there was a partial inhibition of sucrose breakdown, glycolysis and respiration. The energy status of the adenine, guanine and uridine nucleotides decreased, but pyrophosphate levels remained high. The inhibition of sucrose breakdown and glycolysis was accompanied by a small increase of sucrose, fructose, glycerate-3-phosphate, phosphenolpyruvate, and pyruvate, a decrease of the acetyl-coenzymeA:coenzymeA ratio, and a small increase of isocitrate and 2-oxoglutarate. These results indicate that carbon fluxes are inhibited at several sites, but the primary site of action of low oxygen is probably in mitochondrial electron transport. Decreasing the oxygen concentration from 21% to 4% also resulted in a partial inhibition of sucrose uptake, a strong inhibition of amino acid synthesis, a decrease of the levels of cofactors including the adenine, guanine and uridine nucleotides and coenzymeA, and attenuated the wounding-induced increase of respiration and invertase and phenylalanine lyase activity in tissue discs. Starch synthesis was maintained at high rates in low oxygen. Anoxia led to a diametrically opposed response, in which glycolysis rose 2-fold to support fermentation, starch synthesis was strongly inhibited, and the level of lactate and the lactate:pyruvate ratio and the triose-phosphate:glycerate-3-phosphate ratio increased dramatically. It is concluded that low oxygen triggers (i) a partial inhibition of respiration leading to a decrease of the cellular energy status and (ii) a parallel inhibition of a wide range of energy-consuming metabolic processes. These results have general implications for understanding the regulation of glycolysis, starch synthesis and other biosynthetic pathways in plants, and reveal a potential role for pyrophosphate in conserving energy and decreasing oxygen consumption.
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PMID:Metabolic activity decreases as an adaptive response to low internal oxygen in growing potato tubers. 1103 Apr 30

Sucrose synthase (SS) activity has been suggested to be a key point of regulation in nodule metabolism since this enzyme is down-regulated in response to different stresses which lead to decreased nitrogen fixation. In soybean, a dramatic decline of SS transcripts has been observed within 1 d from the onset of drought. Such a quick response suggests mediation by a signal transduction molecule. Abscisic acid (ABA) is a likely candidate to act as such a molecule as it mediates in a significant number of plant responses to environmental constraints. The hypothesis of ABA controlling nodule metabolism was approached in this work by assessing nodule responses to exogenous ABA supply in pea. Under the experimental conditions, ABA did not affect plant biomass, nodule numbers or dry weight. However, nitrogen fixation rate was reduced by 70% within 5 d and by 80% after 9 d leading to a reduced plant organic nitrogen content. Leghaemoglobin (Lb) content declined in parallel with that of nitrogen fixation. SS activity, however, was not affected by ABA treatment, and neither were the activities of the enzymes aspartate amino transferase, alkaline invertase, malate dehydrogenase, glutamate synthase, uridine diphosphoglucose pyrophosphorylase, isocitrate dehydrogenase, and glutamine synthetase. Nodule bacteroid-soluble protein content was reduced in nodules only after 9 d of ABA treatment. These results do not support the hypothesis that ABA directly regulates SS activity. However, they do suggest the occurrence of at least two different control pathways in nodules under environmental constraints, which include ABA being involved in a Lb/oxygen-related control of nitrogen fixation.
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PMID:Abscisic acid induces a decline in nitrogen fixation that involves leghaemoglobin, but is independent of sucrose synthase activity. 1128 73


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