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)

A phytohemagglutinin extract is prepared from raw kidney beans (Phaseolus vulgaris) and incorporated at a level of 1% (dry matter) in the diet of young growing rats. Beside a decrease of feed intakes, the main effects of the experimental diet are the following : growth depression, decrease of dry matter and protein digestibility and hypoglycemia. Biological value, organs weight (liver, kidneys, spleen) did not change significantly. The hemagglutinin extract induces an inhibition of saccharase activity whereas (Na+-K+)-ATPase remains unchanged. Growth depressing effect may be due to an alteration of hydrolysis and absorption mechanisms at the level of brush border of enterocytes.
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PMID:[Effects of a phytohemagglutinin extract on growth, nitrogen digestibility and the activity of invertase and (Na+-K+)-ATPase in the intestinal mucosa of the rat]. 23 10

Infants and young children are particularly susceptible to a recently identified viral enteritis which is highly contagious and seems both common and universal. In this disease, virus invades the upper intestinal epithelium, causing acute diarrhoea with early fever and vomiting. We studied a similar disease in pigs, infecting three-week-old animals with transmissible gastroenteritis virus (TGE), which also invades the upper intestinal epithelium. In this model, diarrhoea is massive 16-40 hours after infection, when stools contain increased electrolytes but no excess of sugar. In the jejunum of intact pigs at the 40-hour stage we found altered Na+ and water flux, decreased mucosal activities of disaccharidases and Na+, K+-ATPase, but normal adenylate cyclase activity. At the same stage the response of Na+ flux to glucose was blunted in jejunal epithelium studied in Ussing short-circuit chambers and in suspensions of villous cells; Cl- flux responded normally to theophylline, and thymidine kinase and sucrase activities of cells isolated from jejunal villi were similar to those found in crypt cells. Probably by 40 hours after infection most virus has been shed from the mucosa. Viral diarrhoea clearly differs from enterotoxigenic diarrhoea. Consideration of its pathogenesis must take into account the dynamic nature of the mucosal epithelium and the factors governing differentiation of enterocytes as they migrate from crypt to villus. Sufficient information is available now to characterize one specific and apparently prevalent viral enteritis in man and to identify additional viral enteritides. There is hope that preventative therapy can be developed. Our understanding of the mechanisms of viral diarrhoea is limited, but the availability of an animal model and the promise of others makes us optimistic that these deficiencies can be remedied. Greater understanding of the pathogenesis of viral diarrhoea should better the active therapy of affected infants and children.
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PMID:Viral gastroenteritis: recent progress, remaining problems. 104 55

PMR1, a Ca(2+)-adenosine triphosphatase (ATPase) homologue in the yeast Saccharomyces cerevisiae localizes to a novel Golgi-like organelle. Consistent with a Golgi localization, the bulk of PMR1 comigrates with Golgi markers in subcellular fractionation experiments, and staining of PMR1 by indirect immunofluorescence reveals a punctate pattern resembling Golgi staining in yeast. However, PMR1 shows only partial colocalization with known Golgi markers, KEX2 and SEC7, in double-label immunofluorescence experiments. The effect of PMR1 on Golgi function is indicated by pleiotropic defects in various Golgi processes in pmr1 mutants, including impaired proteolytic processing of pro-alpha factor and incomplete outer chain glycosylation of invertase. Consistent with the proposed role of PMR1 as a Ca2+ pump, these defects are reversed by the addition of millimolar levels of extracellular Ca2+, suggesting that Ca2+ disposition is essential to normal Golgi function. Absence of PMR1 function partially suppresses the temperature-sensitive growth defects of several sec mutants, and overexpression of PMR1 restricts the growth of others. Some of these interactions are modulated by changes in external Ca2+ concentrations. These results imply a global role for Ca2+ in the proper function of components governing transit and processing through the secretory pathway.
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PMID:The yeast Ca(2+)-ATPase homologue, PMR1, is required for normal Golgi function and localizes in a novel Golgi-like distribution. 137 56

The vacuolar ATPase of the yeast Saccharomyces cerevisiae acidifies the vacuolar lumen and generates an electrochemical gradient across the vacuole membrane. We have investigated the role of compartment acidification of the vacuolar system in the sorting of vacuolar proteins. Strains with chromosomal disruptions of genes (delta vat) encoding the A (69 x 10(3) M(r)), B (57 x 10(3) M(r)) or c (16 x 10(3) M(r)) subunits of the vacuolar ATPase accumulate and secrete precursor forms of the soluble vacuolar hydrolases carboxypeptidase Y and proteinase A. A kinetic analysis suggests that these precursor proteins accumulate in, and are secreted from, the Golgi complex or post-Golgi vesicles. In addition, subcellular fractionation shows that vacuolar hydrolase-invertase hybrid proteins are inefficiently localized to the vacuole in delta vat strains. This result suggests that the vat mutations cause a steady-state defect in vacuolar protein sorting. The vat mutations also affect the sorting of vacuolar membrane proteins. Precursor forms of alkaline phosphatase are accumulated in vat mutant cells, but to a lesser extent than is seen for the soluble vacuolar hydrolases. This finding, coupled with the insensitivity of alkaline phosphatase to the ATPase inhibitor bafilomycin A1, suggests that vacuolar membrane protein sorting is less sensitive to changes in lumenal pH when compared with the targeting of soluble vacuolar proteins. These results indicate that acidification of the vacuolar system is important for efficient sorting of soluble proteins to the vacuole.
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PMID:Mutations in the yeast vacuolar ATPase result in the mislocalization of vacuolar proteins. 149 Dec 35

The common hookworm (Ancylostoma ceylanicum) infection of humans was studied in golden hamsters model system. Significant biochemical modulations were observed in hamster jejunal brush border membrane (BBM), the primary site of infection. Analysis of BBM at the peak of infection (3-weeks) revealed a marked decrease in the activities of sucrase, lactase and maltase, while activities of alkaline phosphatase, (Ca2+ + Mg2+)-ATPase and gamma-glutamyl transpeptidase were increased. Kinetic studies conducted with maltase, a superficially localised enzyme of jejunal BBM, revealed loss of enzyme active site during the infection. Among other constituents, the levels of cholesterol and triglycerides were significantly decreased with slight increase in phospholipid content in the infected animals. The hookworm infection also caused a decline in total hexose content indicating an altered membrane glycocalyx. Conversely, there was significant enhancement of hydroxyproline and sialic acid contents. SDS-PAGE analysis showed an enhancement in both low and high molecular weight proteins in jejunal BBM preparations of the infected group. Gel electrophoresis of glycoproteins further revealed the appearance of two additional peaks in the low molecular weight region and concomitant disappearance of a peak in the high molecular weight region. These results strongly support the view that the hookworm infection causes severe damage not to the site of attachment alone but also to the entire cell lining of the jejunum and therefore could influence overall digestion and absorption.
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PMID:Biochemical analysis of jejunal brush border membrane of golden hamster: pathogenic modulations due to ancylostomiasis. 159 19

Oral administration of the antiulcerogenic drug, cimetidine, was studied on kidney-bound hydrolytic enzymes at three different dose levels (30 mg, 100 mg, and 2000 mg/kg body weight) and for single administration for 2 and 24 h, and daily administration for 15 days in mice. It significantly inhibited Na+, K(+)-ATPase, Mg(2+)-ATPase, and Ca2+, Mg(2+)-ATPase in the isolated basolateral membrane (BLM). Brush-border-membrane-(BBM)-associated enzymes, sucrase, lactase, maltase, leucine aminopeptidase, and alkaline phosphatase also showed a marked reduction. Substrate saturation kinetics revealed the nature of inhibition was of mixed type in the case of sucrase, lactase, maltase, and alkaline phosphatase (Km was increased, while Vmax decreased), whereas it was of non-competitive type for leucine aminopeptidase (Km was unchanged, while Vmax decreased). In vitro addition of cimetidine (5-20 mM) to the BBM also inhibited the enzyme activity. Dixon plot produced the inhibition constant (Ki) for cimetidine in the case of maltase, alkaline phosphatase, and leucine aminopeptidase in the order of 14.83, 32.83 and 11.5 mM, respectively. Analysis of lipids revealed a significant reduction in BBM-associated phospholipid and phospholipid/cholesterol molar ratio, while the neutral lipid fraction, i.e., cholesterol and triglycerides were not altered. Free fatty acid exhibited an increase after drug treatment, which was significant at higher dose after 24 h of single and 15 days of daily treatment. BLM-associated lipids did not exhibit any significant change. Cimetidine-induced depression in renal BLM- and BBM-associated disaccharidases and ATPases, at least at the higher dose level, may have serious consequences in the absorption of end-product nutrients.
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PMID:Depression of membrane-bound hydrolases by cimetidine in mouse renal basolateral and brush border. 183 34

The effect of methylglyoxal on protein -SH and -NH2 groups in cytosolic and membranous fractions of epithelial cells lining the gastrointestinal tract of rat was investigated, using isolated villus and crypt cells (enterocytes) and colonocytes. It was found that 11-12% cytosolic protein -SH and 14-17% membrane protein -SH groups were lost when villus and crypt cells were treated with 2 mM methylglyoxal. In colonocytes, the corresponding loss in protein -SH groups was 46 and 30% under the same treatment. Similarly, 27-37% protein -NH2 group in the cytosolic fraction and 18-19% protein -NH2 group in membranous fractions of the enterocytes were lost by 2 mM methylglyoxal treatment. In colonocytes, the loss of protein -NH2 group was 30 and 15% in cytosolic and membranous fractions, respectively, under the same treatment. Effect of methylglyoxal on activity of various brush border enzymes such as alkaline phosphatase, gamma-glutamyl transpeptidase, leucine aminopeptidase, Mg2(+)-ATPase, sucrase and lactase was also studied. Alkaline phosphatase and gamma-glutamyl transpeptidase activities were inhibited to the extent of 30 and 15% respectively. There was no significant change in the activities of other enzymes after treating the brush border vesicles with 2 mM methylglyoxal. These findings show that methylglyoxal can cause loss of protein thiol and amino groups and enzyme activity in mucosal cells of rat gastrointestinal tract and the effect is more pronounced in colonocytes, which are in constant contact with bacterial metabolites.
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PMID:Effect of methylglyoxal on protein thiol and amino groups in isolated rat enterocytes and colonocytes and activity of various brush border enzymes. 234 Nov 60

The effect of vitamin A deficiency on the intestinal absorption of nutrients and the activities of brush border enzymes were studied in albino rats. Intestinal uptakes of D-glucose, L-methionine, L-tryptophan and L-histidine were significantly greater in vitamin A-deficient animals than in controls. The specific activities of total adenosine triphosphatase (ATPase), ouabain-sensitive ATPase, maltase and sucrase in the intestinal mucosa of vitamin A-deprived rats were 121, 124, 131 and 134 per cent respectively, of the corresponding values in control animals. The DNA content of the small intestine in vitamin A-deficient rats was 36.5 per cent lower than in control rats. The stimulation in digestive and absorptive capacity appears to be an adaptive change in vitamin A-deficiency which decreases the intestinal cell population.
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PMID:Effect of vitamin A deficiency on rat intestinal digestive & absorptive functions. 253 19

Brush-border and basal-lateral membranes were prepared from rabbit intestinal epithelial cells by differential centrifugation and MgCl2 precipitation. The ADP-ribosylation of proteins in these fractions when incubated with [adenylate-32P]NAD+ and cholera toxin was investigated. Three proteins of molecular mass 45, 40 and 37 kDa were labelled in a toxin-dependent manner in each membrane fraction. The incorporation of 32P-labelled ADP-ribose was 18-fold greater in brush-border membranes than in basal-lateral membranes, comparable to the enrichment of sucrase (marker enzyme for the brush border) in these membranes. There was a 20% release of the 40 and 45 kDa proteins from the brush-border membrane following this ADP-ribosylation. Activation of adenylate cyclase by both cholera toxin and sodium fluoride was 2.7- and 2.3-fold greater, respectively, in basal-lateral membranes than in brush-border membranes, comparable to the enrichment of Na+/K+-ATPase (marker enzyme for the basal-lateral membrane) in these membranes. The effect of sodium fluoride on membranes pretreated with cholera toxin revealed no increase in adenylate cyclase activity above that due to the toxin. This presumably means that both toxin and fluoride activate adenylate cyclase by the same regulatory protein. The results show that cholera toxin catalyzes the ADP-ribosylation of regulatory proteins in the brush-border membrane, and these proteins then migrate to the basal-lateral membrane where they activate the catalytic component of adenylate cyclase.
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PMID:The activation of rabbit intestinal adenylate cyclase by cholera toxin. 260 57

To investigate further the pathophysiology of rotavirus-induced diarrhea, changes in specific activities of eight relevant intestinal enzymes [alkaline phosphatase, thymidine kinase, lactase, maltase, sucrase, Na+,K+-adenosine triphosphatase (ATPase), adenylate and guanylate cyclases] were measured following infection of suckling mice with murine rotavirus (epizootic diarrhea of infant mouse strain) and compared with age-matched control mice. The concentration of lactose within the lumen of the gastrointestinal tract during infection was also measured. During the course of infection, activities of alkaline phosphatase and lactase decreased, whilst the activity of thymidine kinase increased. Precocious maturation profiles of sucrase and maltase enzymes were observed. No significant changes were detected in the activities of Na+,K+-ATPase or the adenylate and guanylate cyclases. These results are discussed in relation to existing and novel hypotheses on the pathogenesis of rotavirus-induced diarrhea.
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PMID:Intestinal enzyme profiles in normal and rotavirus-infected mice. 289 74


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