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)

Yeast mutants with glucose-insensitive formation of mitochondrial enzymes were isolated starting with a strain completely lacking alcohol dehydrogenase activity. The mutations could uniquely be attributed to a single nuclear gene, designated CCR80. They were largely dominant. Glucose-resistant enzyme formation was most prominent with regard to mitochondrial enzymes succinate dehydrogenase and NADH: cytochrome c oxidoreductase. The effect of CCR80r mutations was rather small but significant on the gluconeogenetic enzymes isocitrate lyase, malate synthase and fructose-1,6-bisphosphatase and on invertase synthesis. The repressive effect of maltose in CCR80r mutants was also reduced showing that glucose-resistance is not caused by a mere hexose uptake defect. This regulatory disorders were not accompanied by reduced levels of glycolytic enzymes or drastically altered levels of glycolytic intermediates. Aerobic fermentation of glucose was almost completely inhibited in the mutants; anaerobic glucose degradation was reduced but not completely abolished. Therefore, the mutants appear to be altered in the regulation of glycolysis. A largely glucose-resistant synthesis of respiratory enzymes is obviously a corollary of this alteration.
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PMID:A yeast mutant with glucose-resistant formation of mitochondrial enzymes. 20 62

A study was made of the enzyme content of the isolated cell walls and of a plasma-membrane preparation obtained by centrifugation after enzymic digestion of the cell walls of baker's yeast. The isolated cell walls showed no hexokinase, alkaline phosphatase, esterase or NADH oxidase activity. It was concluded that these enzymes exist only in the interior of the cell. Further, only a negligible activity of deamidase was detectable in the cell walls. Noticeable amounts of saccharase, phosphatases hydrolysing p-nitrophenyl phosphate, ATP, ADP, thiamin pyrophosphate and PP(i), with optimum activity at pH3-4, and an activity of Mg(2+)-dependent adenosine triphosphatase at neutral pH, were found in the isolated cell walls. During enzymic digestion, the other activities appearing in the cell walls were mostly released into the medium, but the bulk of the Mg(2+)-dependent adenosine triphosphatase remained in the plasma-membrane preparation. Accordingly, it may be assumed that the enzymes released into the medium during digestion are located in the cell wall outside the plasma membrane, whereas the Mg(2+)-dependent adenosine triphosphatase is an enzyme of the plasma membrane. This enzyme differs from the phosphatases with pH optima in the range pH3-4 with regard to location, pH optimum, substrate specificity and different requirement of activators.
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PMID:The enzymic composition of the isolated cell wall and plasma membrane of baker's yeast. 431 24

Current hospital practice for testing renal function is to use the creatinine clearance test. Inulin clearance, an inherently more accurate procedure, currently is only carried out by specialized laboratories because there is not a simple biochemical assay for inulin, that is, an assay that could be carried out by any laboratory without special facilities. We have developed a simple enzymatic assay system for measuring inulin in plasma and urine. The procedure uses a beta-fructofuranosidase immobilized on Concanavalin A to convert inulin to fructose. Fructose is then measured by measuring the NADH----NAD conversion produced when fructose is converted to sorbitol by the enzyme sorbitol dehydrogenase. Kinetic parameters, binding capacities, and operating conditions for the immobilized beta-fructofuranosidase were determined as well as general operating parameters for the complete assay system. This system offers the potential for replacing the creatinine clearance test as the assay of choice for renal function.
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PMID:A simple inulin assay for renal clearance determination using an immobilized beta-fructofuranosidase. 659 2

A coupled enzymatic method for the assay of invertase is described. In this method, the fructose produced from sucrose by invertase action is converted to D-sorbitol by sorbitol dehydrogenase. The reaction is monitored by the decrease in A340 mm due to the consumption of NADH. The technique is simple, sensitive, and accurate, and compares well with alternative methods which rely on determination of glucose formed in the invertase reaction.
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PMID:A simplified method for measuring activity of beta-D-fructofuranoside fructohydrolase (invertase). 667 34

Previously, we described a mutation glr1-1 in Saccharomyces carlsbergensis which pleiotropically relieves the synthesis of the following enzymes from glucose repression: maltase, galactokinase, alpha-galactosidase, NADH:cytochrome c reductase, and cytochrome c oxidase (C. A. Michels and A. Romanowski, J. Bacteriol, 143:674-679, 1980.) In this report, we demonstrate that glr1-1 and two other alleles, glr1-3 and glr1-16, are also insensitive to the glucose repression of invertase synthesis. Determinations of the levels of hexokinase activity and the rate of glucose transport in these mutants show that both are reduced as compared with the parent strain. Complementation tests and genetic analysis indicate that the glr1 mutations are allelic to HXK2, the structural gene for hexokinase B. The significance of this result is discussed with regard to the mechanism of glucose repression in S. carlsbergensis.
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PMID:Pleiotropic mutations regulating resistance to glucose repression in Saccharomyces carlsbergensis are allelic to the structural gene for hexokinase B. 684 88

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

The first step in sucrose use by maize kernels produces fructose, regardless of whether the initial reaction is catalyzed by an invertase or the reversible sucrose synthase. This fructose can enter subsequent metabolism via hexokinase, or in maize kernels, by a sorbitol dehydrogenase that reversibly converts fructose + NADH to sorbitol + NAD. High levels of SDH activity suggest that kernels synthesize considerable amounts of sorbitol, but the molecular mechanism and functional role for this process have remained equivocal. To gain insights on the role of sorbitol synthesis in maize endosperm we cloned and characterized the transcriptional control of the maize sorbitol dehydrogenase (Sdh1) gene. Data indicated that Sdh1 was essentially kernel- and endosperm-specific, with maximal expression at both the mRNA and enzyme activity levels during early kernel development. Expression was elevated in high-sugar mutants (sugary1, shrunken2), also by sugar injections, and was more pronounced when transfected tissues were incubated at low oxygen concentrations. Control of Sdh1 expression in our transient assays was largely dependent on the first intron of Sdh1. We speculate that SDH activity may represent an adaptation to the high-sugar/low-oxygen environment of the endosperm. Under these conditions, the NADH-dependent reduction of fructose to sorbitol would regenerate NAD[+], thus contributing to the maintenance of the redox and energy status of the cell.
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PMID:Sugar levels modulate sorbitol dehydrogenase expression in maize. 1856 93

Seeds of pea (Pisum sativum L.) were germinated for 5d by soaking in distilled water or 5mM cadmium nitrate. The relationships among cadmium stress, germination rate, changes in respiratory enzyme activities and carbohydrates mobilization were studied. Two cell fractions were obtained from embryonic axis: (1) mitochondria, used to determine enzyme activities of citric acid cycle and electron transport chain, and (2) soluble, to measure some enzyme activities involved in fermentation and pentose phosphate pathway. Activities of malate- and succinate-dehydrogenases (MDH, SDH) and NADH- and succinate-cytochrome c reductases (NCCR, SCCR) were rapidly inhibited, while cytochrome c oxidase (CCO) was unaltered by cadmium treatment. However, this stimulated the NADPH-generating enzyme activities of the pentose phosphate pathway, glucose-6-phosphate- and 6-phosphogluconate-dehydrogenases (G6PDH, 6PGDH), as well as enzyme activity of fermentation, alcohol dehydrogenase (ADH), with concomitant inhibition in the capacity of enzyme inactivator (INADH). Moreover, Cd restricted carbohydrate mobilization in the embryonic axis. Almost no glucose and less than 7% of control fructose and total soluble sugars were available in the embryo tissues after 5d of exposure to cadmium. Cotyledonary invertase isoenzyme activity was also inhibited by Cd. The results indicate that cadmium induces disorder in the resumption of respiration in germinating pea seeds. The contribution of Cd-stimulated alternative metabolic pathways to compensate for the failure in mitochondrial respiration is discussed in relation to the delay in seed germination and embryonic axis growth.
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PMID:Respiratory metabolism in the embryonic axis of germinating pea seed exposed to cadmium. 1876 Apr 97

A "smart" biofuel cell switchable ON and OFF upon application of several chemical signals processed by an enzyme logic network was designed. The biocomputing system performing logic operations on the input signals was composed of four enzymes: alcohol dehydrogenase (ADH), amyloglucosidase (AGS), invertase (INV) and glucose dehydrogenase (GDH). These enzymes were activated by different combinations of chemical input signals: NADH, acetaldehyde, maltose and sucrose. The sequence of biochemical reactions catalyzed by the enzymes models a logic network composed of concatenated AND/OR gates. Upon application of specific "successful" patterns of the chemical input signals, the cascade of biochemical reactions resulted in the formation of gluconic acid, thus producing acidic pH in the solution. This resulted in the activation of a pH-sensitive redox-polymer-modified cathode in the biofuel cell, thus, switching ON the entire cell and dramatically increasing its power output. Application of another chemical signal (urea in the presence of urease) resulted in the return to the initial neutral pH value, when the O(2)-reducing cathode and the entire cell are in the mute state. The reversible activation-inactivation of the biofuel cell was controlled by the enzymatic reactions logically processing a number of chemical input signals applied in different combinations. The studied biofuel cell exemplifies a new kind of bioelectronic device where the bioelectronic function is controlled by a biocomputing system. Such devices will provide a new dimension in bioelectronics and biocomputing benefiting from the integration of both concepts.
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PMID:Biofuel cell controlled by enzyme logic network--approaching physiologically regulated devices. 1935 82

The logic gates NAND/NOR were mimicked by enzyme biocatalyzed reactions activated by sucrose, maltose and phosphate. The subunits performing AND/OR Boolean logic operations were designed using maltose phosphorylase and cooperative work of invertase/amyloglucosidase, respectively. Glucose produced as the output signal from the AND/OR subunits was applied as the input signal for the INVERTER gate composed of alcohol dehydrogenase, glucose oxidase, microperoxidase-11, ethanol and NAD(+), which generated the final output in the form of NADH inverting the logic signal from 0 to 1 or from 1 to 0. The final output signal was amplified by a self-promoting biocatalytic system. In order to fulfill the Boolean properties of associativity and commutativity in logic networks, the final NADH output signal was converted to the initial signals of maltose and phosphate, thus allowing assembling of the same standard units in concatenated sequences. The designed modular approach, signal amplification and conversion processes open the way toward complex logic networks composed of standard elements resembling electronic integrated circuitries.
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PMID:Enzyme-based NAND and NOR logic gates with modular design. 1990 34


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