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)

In vivo jejunal transport of amino acids, monosaccharides, sodium, and electrolytes were studied in rats made nephrotic with puromycin aminonucleoside (PAN) and in pair-fed controls. Studies were performed 14 days after a single intravenous dose of PAN when rats were no longer edematous, but were still hypoproteinemic. There was decreased absorption of glucose, 3-0-methyl glucose, glycine, phenylalanine, histidine, water, and sodium in the nephrotic animals but transport of fructose, lysine and potassium was similar in the nephrotic and control animals. Enzyme kinetic studies for glucose transport showed a mixed type of inhibition affecting both Vm and Km. The jejunal mucosa of nephrotic and control rats had similar ATP content and enzyme activity for lactase, sucrase, maltase and (Na-K)-ATPase and the ratios of RNA to DNA were similar in the nephrotic and control rats. No abnormality of the jejunum was detected by light or electron microscopy. The data suggest that the impairment of absorption is a result of decreased activity of jejunal membrane carrier mechanisms. The altered transport may be secondary to effects related to the metabolic consequences of nephrotic syndrome and does not appear to be related to acute purine aminonucleoside toxicity, edema or malnutrition.
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PMID:Jejunal transport in experimental nephrotic syndrome. 662 9

The carboxymethylcellulose-gelatine carrier system was investigated for invertase immobilization. Chromium (III) acetate, chromium (III) sulphate and potassium chromium (III) sulphate were used as cross-linking agents. Effect of carboxymethylcellulose-gelatine ratio and cross-linker concentration on immobilized enzyme activity were analysed. Reusability of immobilized enzyme was also investigated. Maximum immobilized enzyme activities were obtained with cross-linkers chromium (III) sulphate (0.004 mol dm-3) and potassium chromium (III) sulphate (0.001 mol dm-3) for a carrier composition of carboxymethylcellulose-gelatine ratio 0.111 (w/w) as 78%.
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PMID:Effect of chromium salts on invertase immobilization onto carboxymethyl-cellulose-gelatine carrier system. 883 Sep 70

To evaluate the possibility that an apical membrane conductive pathway for oxalate is present in the rabbit distal ileum, we studied oxalate ([14C]oxalate) and chloride (36Cl) uptake into brush-border membrane vesicles enriched 15- to 18-fold in sucrase activity. Voltage-sensitive pathways for oxalate and chloride were identified by the stimulation of uptake provided by an inwardly directed potassium diffusion potential in the presence of valinomycin. Additionally, outwardly directed oxalate (or chloride) gradients stimulated [14C]oxalate (or 36Cl) uptake to a greater degree in the absence of valinomycin (when intracellular and extracellular potassium are equal) than in the presence of valinomycin. Voltage-dependent anion uptake was poorly saturable: apparent affinity constants were 141 +/- 17 and 126 +/- 8 mM for chloride and oxalate, respectively. Activation energies for the voltage-dependent uptake processes were low: 4.7 and 6.3 kcal/mol for chloride and oxalate, respectively. Sensitivity profiles of voltage-dependent chloride and oxalate uptake to anion transport inhibitors were similar. We conclude that an anion conductance is present in the apical membranes of ileal enterocytes and that this conductance is a candidate pathway for oxalate efflux from the enterocyte during transepithelial oxalate secretion.
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PMID:Conductive pathways for chloride and oxalate in rabbit ileal brush-border membrane vesicles. 973 Sep 58

The midgut of the tobacco hornworm, Manduca sexta, actively secretes potassium ions. This can be measured as short-circuit current (I(sc)) with the midgut mounted in an Ussing chamber and superfused with a high-K(+) saline containing as its major osmolyte 166 mM sucrose. Iso-osmotic substitution of sucrose by non-metabolisable compounds (mannitol, urea, NaCl and the polyethylene glycols 200, 400 and 600) led to a dramatic, though reversible, drop in the current. Acarbose, a specific inhibitor of invertase (sucrase) in vertebrates and insects, had no detectable influence on I(sc). Unexpectedly, after replacing sucrose iso-osmotically with the saccharides glucose, fructose, trehalose or raffinose, the K(+) current could no longer be supported. However, all osmolytes smaller than sucrose (except for NaCl), metabolisable or not, initiated an immediate, quite uniform but transient, increase in I(sc) by about 20%, before its eventual decline far below the control value. Hypo-osmotic treatment by omission of sucrose also transiently increased the K(+) current. Small osmolytes substituted for sucrose caused no transient I(sc) stimulation when the epithelium had been challenged before with hypo-osmolarity; however, the eventual decline in I(sc) could not be prevented. Our data seem inconsistent with a role of sucrose as energiser or simple osmolyte. Rather, we discuss here its possible role as analogous to that of sucrose in lower eukaryotes or plants, as an extra- and/or intracellular "compatible osmolyte" that stabilises structure and/or function of the proteins implicated in K(+) transport.
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PMID:K+ transport in the caterpillar intestine epithelium: role of osmolytes for the K+-secretory capacity of the tobacco hornworm midgut. 1532 45

In an in vitro system comprising a yeast cell-free translation system, yeast microsomes and mRNA encoding prepro-alpha-factor, the translocation of this protein across the membrane of the microsomal vesicle and its glycosylation could b uncoupled from its translation. Such post-translational processing is dependent upon the presence of ATP in the system. It is not, however, affected by a variety of uncouplers, ionophores or inhibitors, including carbonyl cyanide m-chlorophenyl hydrazone (CCCP), valinomycin, nigericin, dinitrophenol (DNP), potassium cyanide (KCN) or N-ethyl maleimide (NEM). This mechanism of translocation is significant as it indicates that a protein of 18 000 daltons is capable of crossing an endoplasmic reticulum-derived membrane post-translationally. For the moment, this phenomenon seems to be restricted to prepro-alpha-factor in the yeast in vitro system. Neither invertase nor IgG chi light chain could be translocated post-translationally in yeast, nor was such processing observed for prepro-alpha-factor in a wheat germ system supplemented with canine pancreatic microsomes.
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PMID:Secretion in yeast: translocation and glycosylation of prepro-alpha-factor in vitro can occur via an ATP-dependent post-translational mechanism. 1595 17

The effect of enteritis on the development of the small intestine was examined in newborn, colostrum-deprived piglets infected with a human isolate of Y. enterocolitica (serotype 0:3, biotype 4) soon after birth. The piglets were killed 3 days (n = 6) or 5 days (n = 8) after infection, or antibiotic therapy was commenced on day 5 and the animals killed on day 14 (n = 5). Compared with the non-infected controls, infected animals had reduced mucosal lactase and sucrase, but not maltase activity, while after antibiotic therapy, previously infected piglets had a lower lactase and a higher maltase and sucrase activity. Lactase activity was significantly reduced in the duodenum and jejunum, and mean values were lower in the ileum, but the difference did not reach significance; maltase activity was greater at all ages from the distal jejunum to the mid-ileum; sucrase activity was reduced in all segments up to day 5 but after antibiotic therapy was increased in the jejunum and appeared early in the ileum. Enzyme profiles were more mature along the crypt-villus axis in some segments of the intestine in previously infected piglets. Sodium-potassium-ATPase activity was unchanged. There was a reduced villus height:crypt depth ratio, crypt hyperplasia and increased crypt cell proliferation. Morphological maturation, indicated by loss of vacuoles and location of the nucleus at the base of the enterocyte, proceeded distally from the duodenum to ileum from 3 to 14 days of age when only the ileum remained immature. In infected piglets, there was reduced vacuolation and earlier location of the nucleus at the base of the cell in the distal intestine. Accelerated maturity of specific disaccharidases and enterocyte morphology in infected piglets appears to be due to physical damage to the mucosa resulting in faster proliferation of crypt cells and migration of enterocytes. It is suggested that this may reduce macromolecular internalisation and impair the ability to utilise dietary carbohydrate and may have long-term effects on growth and immunological responses of the gut.
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PMID:Impact of Yersinia enterocolitica enteritis on disaccharidase activity and small intestinal morphology in colostrum-deprived newborn piglets. 1603 44

The osmotolerance of Saccharomyces rouxii 48-28 was confirmed with both NaCl- and KCl-fortified growth media, with more tolerance being exhibited for the potassium salt. Washed and buffered cells from unfortified medium were challenged with a variety of compounds (and also with physical treatments) that potentially would elicit membrane perturbations. The efficacy of these brief treatments was judged primarily by monitoring subsequent viability. Change in the degree of expression of beta-fructofuranosidase (EC 3.2.1.26), which is cryptic in young cells of S. rouxii, was a second criterion. There was a linear correlation between cell death and enzyme expression for treatments with polyenes, detergents, some organic solvents which did not denature the enzyme, and various freeze-thaw regimens in graded amounts of glycerol. The species is relatively insensitive to polyene antimycotics, the order of decreasing effect being filipin, nystatin, and amphotericin B. S. rouxii was found to be less sensitive to osmotic shock than is Saccharomyces cerevisiae, but in neither species is beta-fructofuranosidase released to the medium. The sensitivity of S. rouxii to ionic detergents, but not to nonionic detergents, was rationalized as being due to cell wall discrimination against larger micelles for the nonionic examples. This was confirmed by showing that protoplasts were sensitive to both classes. In cultures older than 5 days the normal agreement between colony-forming units and methylene blue exclusion (another test of viability) no longer held. Delayed fermentation of sucrose by S. rouxii, which is a diagnostic feature of the species, is explained by death of some cells, expression of their beta-fructofuranosidase, and utilization of the monosaccharides by the surviving cells.
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PMID:Effects of Polyenes, Detergents, and Other Potential Membrane Perturbants on an Osmotolerant Yeast, Saccharomyces rouxii. 1634 36

Freshly cut disks of beetroot tissue develop high rates of respiration, uptake of phosphate and activity of the enzyme invertase after having been washed for 18 hours in 0.01 m potassium maleate.Incubation of the disks in solutions of indole-3-acetic acid or kinetin completely prevented the development of the higher activities in all 3 systems assayed, while incubation in gibberellic acid had no inhibitory effect. Using a series of synthetic plant growth regulating compounds it was possible to establish that there was no correlation between the activity of the compound as an auxin and the ability of the compound to prevent the development of the enhanced rates of metabolism.
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PMID:The influence of growth regulating substances on the development of enhanced metabolic rates in thin slices of beetroot storage tissue. 1665 81

A salt-sensitive genotype of Solanum lycopersicum cv. Volgogradskij was submitted to a 6-day treatment with high salt (100, 200 mM NaCl), allowed to recover for 6 days and then submitted to a second period of salt stress in order to study changes in carbohydrate metabolism related to salt adaptation. The ion, soluble sugar and starch contents, as well as sucrose biosynthetic and sugar mobilizing enzyme activities and transcript levels were determined during the salt stress/recovery/stress cycle. Sodium ions were found to accumulate preferentially in old leaves. Young leaves accumulated lower levels of sodium ions but maintained control levels of potassium ions. Hexoses accumulated to higher levels and starch was better maintained in young compared to old leaves during the two salt treatments. Sucrose accumulated dramatically only in old leaves during the initial salt treatment. Sugar accumulation was not related to decreases in the activities of sugar mobilizing enzymes, acid (EC 3.2.1.25) and neutral (EC 3.2.1.26) invertases, sucrose synthase (EC 2.4.1.13) and hexokinase (EC 2.7.1.1). The activity of the biosynthetic enzyme sucrose phosphate synthase (EC 2.3.1.14) was linked to changes in sucrose levels but not with transcript levels. These results point to the importance of post-transcriptional regulation. Transcriptional regulation could nevertheless be seen in the down-regulation of ribulose bisphosphate carboxylase small subunit (EC 4.1.1.39) in old compared to young leaves, but this was not related to sugar levels.
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PMID:Adaptive response to salt involving carbohydrate metabolism in leaves of a salt-sensitive tomato cultivar. 1762 95

In Arabidopsis thaliana, six vacuolar Na(+)/H(+) antiporters (AtNHX1-6) were identified. Among them, AtNHX1, 2 and 5 are functional Na(+)/H(+) antiporters with the most abundant expression levels in seedling shoots and roots. However, the expression of AtNHX3 in Arabidopsis can only be detected by RT-PCR, and its physiological function still remains unclear. In this work, we demonstrate that constitutive expression of AtNHX3 in sugar beet (Beta vulgaris L.) conferred augmented resistance to high salinity on transgenic plants. In the presence of 300 or 500 mm NaCl, transgenic plants showed very high potassium accumulation in the roots and storage roots. Furthermore, the transcripts of sucrose phosphate synthase (SPS), sucrose synthase (SS) and cell wall sucrose invertase (SI) genes were maintained in transgenic plants. The accumulation of soluble sugar in the storage roots of transgenic plants grown under high salt stress condition was also higher. Our results implicate that AtNHX3 is also a functional antiporter responsible for salt tolerance by mediating K(+)/H(+) exchange in higher plants. The salt accumulation in leaves but not in the storage roots, and the increased yield of storage roots with enhanced constituent soluble sugar contents under salt stress condition demonstrate a great potential use of this gene in improving the quality and yield of crop plants.
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PMID:Transgenic salt-tolerant sugar beet (Beta vulgaris L.) constitutively expressing an Arabidopsis thaliana vacuolar Na/H antiporter gene, AtNHX3, accumulates more soluble sugar but less salt in storage roots. 1851 17


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