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 small intestinal disaccharidase activity and its daily variation in the diabetic rat have not been well described. Therefore, the small intestinal disaccharidase (maltase, lactase and sucrase) activity and its daily profile were studied in streptozotocin-induced diabetic rats under physiological conditions. In diabetic rats, a similar pattern of diurnal variation of disaccharidase activity to control rats was observed, while the relationships between daily change of disaccharidase activity and that of food consumption suggested that there was a different mechanism of diurnal variation in diabetic rats. On the other hand, a significant increase of mean 24-h lactase and sucrase activities was noted in diabetic rats, while that of maltase was not significant. Using the in vitro incubation method, a significant correlation between glucose concentration and lactase or sucrase activity but not maltase activity was observed. However, insulin showed no effect on disaccharidase activity. Thus we clarified the presence of a diurnal variation of disaccharidase activity and an increase in its activity in diabetic rats. This change was suggested to be derived from high plasma glucose level.
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PMID:Diurnal variation and increase of disaccharidase activity in diabetic rats. 145 37

mRNA steady-state levels and activities of enzymes of intermediary carbon metabolism (hexokinase, phosphoglucoisomerase, phosphofructokinase, glucose-6-phosphate dehydrogenase, phosphoglucomutase) and glucose-regulated enzymes (pyruvate decarboxylase, pyruvate dehydrogenase, invertase, alcohol dehydrogenase) were determined in glucose-limited continuous cultures of an industrial strain of Saccharomyces cerevisiae at different dilution rates (D) ranging from 0.05 to 0.315 h-1. The activity of most enzymes measured remained constant over this range except for alcohol dehydrogenase I/II which decreased proportionally with increasing dilution rate. A decrease in phosphoglucomutase activity occurred with increasing dilution rate but reached a minimum at D 0.2 h-1 and from thereon remained constant. A decrease in pyruvate decarboxylase activity and a slight decrease in phosphoglucoisomerase activity was observed. At D 0.29/0.315 h-1, at the onset of the Crabtree effect, most glycolytic enzymes remained constant except for pyruvate decarboxylase and glucose-6-phosphate dehydrogenase which increased at D 0.315 h-1 and alcohol dehydrogenase I/II which decreased. The ADHI/II and PDC1 mRNA levels obtained at the different dilution rates were in accordance with the activity measurements. The mRNA level of HXK1 decreased with increasing dilution rates, whereas the transcription of HXK2 increased. Pyruvate dehydrogenase (PDA1) and PGI1 mRNA fluctuated but no significant change could be detected. These results indicate that there is no transcriptional or translational regulation of glycolytic flux between D 0.05 h-1 and 0.315 h-1 except at the branch point between oxidative and fermentative metabolism (pyruvate decarboxylase/pyruvate dehydrogenase) at D 0.315 h-1. Surprisingly regulation of the Crabtree effect does not seem to involve transcriptional regulation of PDA1.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Analysis of transcription and translation of glycolytic enzymes in glucose-limited continuous cultures of Saccharomyces cerevisiae. 148 26

Alkaline invertase from sprouting soybean (Glycine max) hypocotyls was purified to apparent electrophoretic homogeneity by consecutive use of DEAE-cellulose, green 19 dye, and Cibacron blue 3GA dye affinity chromatography. This protocol produced about a 100-fold purification with about a 11% yield. The purified protein had a specific activity of 48 mumol of glucose produced mg-1 protein min-1 (pH 7.0) and showed a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (PAGE) (58 kDa) and in native PAGE, as indicated by both protein and activity staining. The native enzyme molecular mass was about 240 kDa, suggesting a homotetrameric structure. The purified enzyme exhibited hyperbolic saturation kinetics with a Km (sucrose) near 10 mM and the enzyme did not utilize raffinose, maltose, lactose, or cellibose as a substrate. Impure alkaline invertase preparations, which contained acid invertase activity, on contrast, showed biphasic curves versus sucrose concentration. Combining equal activities of purified alkaline invertase with acid invertase resulted in a biphasic response, but there was a transition to hyperbolic saturation kinetics when the activity ratio, alkaline: acid invertase, was increased above unity. Alkaline invertase activity was inhibited by HgCl2, pridoxal phosphate, and Tris with respective Ki values near 2 microM, 5 microM, and 4 mM. Glycoprotein staining (periodic acid-Schiff method) was negative and alkaline invertase did not bind to two immobilized lectins, concanavalin A and wheat germ agglutinin; hence, the enzyme apparently is not a glycoprotein. The purified alkaline invertase, and a purified soybean acid invertase, was used to raise rabbit polyclonal antibodies. The alkaline invertase antibody preparation was specific for alkaline invertase and cross-reacted with alkaline invertases from other plants. Neither purified soybean alkaline invertases nor the crude enzyme from several plants cross-reacted with the soybean acid invertase antibody.
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PMID:Biochemical and immunological properties of alkaline invertase isolated from sprouting soybean hypocotyls. 157 18

Following massive small bowel resection, the remaining small bowel increases in mucosal weight, protein, deoxyribonucleic acid (DNA) content and absorptive function. Enteral nutrients are known to be important in stimulating this response. Recently, glutamine has been described as an essential fuel for the small intestinal mucosa and is thought to be trophic to the small bowel. We investigated if glutamine, when added to the diet in large quantities, might stimulate mucosal adaptation beyond that which normally occurs following physiologic feedings. Male Sprague-Dawley rats were placed on powdered rat chow supplemented with either 5% glutamine, 5% glycine or 5% glucose. After 4 days rats underwent 70% jejunoileal resection. Fourteen days after resection, protein, DNA and sucrase activity in the duodenum of the glutaminefed animals were all significantly lower than results from both the glycine and glucose groups. Duodenal mucosal weight was lower in the glutamine group than in the glycine group. In the ileum, DNA content was significantly lower for the glutamine group than the glycine group. These results suggest that high concentrations of glutamine in the diet can have negative effects on intestinal adaptation.
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PMID:Effects of oral supplementation of glutamine on small intestinal mucosal mass following resection. 157

The effect of total parenteral nutrition on nutrients absorption and glycoprotein changes of brush border membrane was examined in rat small intestine. In total parenteral nutrition rats, a marked decrease in activity of brush border enzymes was observed mainly in the proximal and middle segments of the intestine. Galactose perfusion of jejunal segment showed that hexose absorption was significantly inhibited, while intestinal absorption of glycine or dipeptide, glycylglycine was not significantly affected by total parenteral nutrition treatment. When brush border membrane glycoprotein profile was examined by [3H]-glucosamine or [3H]-fucose incorporation into jejunal loops, significant changes were observed in the glycoprotein pattern of brush border membrane especially in the high molecular weight range over 120 kDa after total parenteral nutrition treatment, suggesting strong dependency of glycoprotein synthesis on luminal substances. Molecular weight of sucrase isomaltase in brush border membrane detected by specific antibody showed no significant difference, however, in total parenteral nutrition and control rats. Also, molecular weight of specific sodium glucose cotransporter of intestinal brush border membrane detected by selective photoaffinity labelling was not altered in total parenteral nutrition rats. It may be that prolonged absence of oral food intake may produce significant biochemical changes in brush border membrane glycoprotein and absorptive capacity of small intestine, but these changes were not observed in all brush border membrane glycoproteins.
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PMID:Changes in intestinal absorption of nutrients and brush border glycoproteins after total parenteral nutrition in rats. 158 92

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

AO-128 is a potent and structurally novel inhibitor of the intestinal disaccharidases, such as maltase and sucrase. Genetically obese-diabetic mice, KKA(y), were used to examine the acute or long-term effectiveness of this compound. AO-128 decreased a postprandial rise in blood glucose after sucrose solution loading dose-dependently; the ED50 to reduce a delta increment of blood glucose by 50% was 0.22 mg/kg. The intestinal sucrase and maltase activities were suppressed to 7 and 48% of the control levels, respectively, at a dose of 0.21 mg/kg. Four-week-old female KKA(y) mice were kept on a laboratory diet containing 10 or 50 ppm of AO-128 for 12 weeks. The high dose of AO-128 reduced food intake and body weight gain throughout the experimental period. On the other hand, the low dose reduced body weight gain for the first 4 weeks without any effect on food intake. Development of the hyperglycemia and hyperinsulinemia characteristic of KKA(y) mice was moderately prevented by the low dose, and completely by the high dose. Hypertriglyceridemia tended to be suppressed by the AO-128 treatment. The high dose decreased the hemoglobin A1 level and parametrial adipose tissue weight. Hepatomegaly and fatty liver were ameliorated by AO-128 dose-dependently. Nephropathy was ameliorated by the high dose. These findings indicate that AO-128 may be useful for treating human obesity and diabetes.
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PMID:Antiobesity and antidiabetic actions of a new potent disaccharidase inhibitor in genetically obese-diabetic mice, KKA(y). 162 84

The function of the SRH1 product, the yeast homologue of the 54 kDa subunit of the mammalian signal recognition particle, has been analyzed using a galactose dependent mutant of the gene. SRH1 has been placed under control of the GAL1 promoter and introduced into a haploid cell that had its chromosomal SRH1 copy disrupted. This mutant grows normally on galactose medium but slows down the growth about 10 h after transfer to glucose medium. At the same time, precursor forms of secretory proteins, alpha-mating factor and invertase, accumulate in the cells. This result indicates that the SRH1 product is involved in translocation of precursors of secretory proteins across the endoplasmic reticulum membrane in yeast cells.
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PMID:SRH1 protein, the yeast homologue of the 54 kDa subunit of signal recognition particle, is involved in ER translocation of secretory proteins. 164 26

Factors, such as insulin, found in human and pig colostrum and mature milk likely influence small intestinal growth and development. Although pharmacologic doses of insulin injected parenterally may accelerate small intestinal development in altricial animals such as the rodent, the effects of oral insulin on intestinal development have not been studied. In the first of two studies, we randomized 2-d-old miniature piglets to receive bottle-feedings of a swine weaning milk formula with (group F + I) or without (group F) the addition of insulin. Serum glucose, insulin, and cortisol were measured before and 1 h after the first feeding the piglets received at our facility. In the second study, piglets were randomized (groups F and F + I) and fed for 6 d, after which blood samples were obtained as in the first experiment. The piglets were then killed and the small intestine removed for analysis. We found no differences between groups in serum glucose, insulin, and cortisol at both 2 and 8 d of age, both before and after feeding. In the second experiment, small intestinal weight was greater in the F + I than in the F group. Although no differences were noted between groups in the jejunum, values were greater for group F + I versus group F for ileal mucosal weight, protein, RNA, lactase, and maltase activities. No differences were found between groups in ileal DNA or sucrase activity. We conclude that the administration of oral insulin stimulated an increase in ileal mass and disaccharidase activity in the newborn miniature pig without apparent concomitant changes in serum glucose, insulin, or cortisol.
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PMID:Oral insulin increases small intestinal mass and disaccharidase activity in the newborn miniature pig. 169 70

Starch digestion and absorption is augmented appreciably by physical processing of grain or legume and by heating to 100 degrees C for several minutes before its ingestion. Starch, a polysaccharide composed of alpha 1,4-linked glucose units (amylose) and alpha 1,4-1,6-linked branched structure (amylopectin), is cleaved in the duodenal cavity by secreted pancreatic alpha-amylase to a disaccharide (maltose), trisaccharide (maltotriose), and branched alpha-dextrins. These final oligosaccharides are hydrolyzed efficiently by complimentary action of three integral brush border enzymes at the intestinal surface: glucoamylase (maltase-glucoamylase, amyloglucosidase), sucrase (maltase-sucrase) and alpha-dextrinase (isomaltase). The final monosaccharide glucose product is then cotransported into the enterocyte along with Na+ by a specific brush border 75-kDa transport protein in the rate-limiting step for overall starch assimilation. By virtue of this sequential luminal and membrane digestion followed by glucose transport, starch is assimilated in a very efficient manner in nonruminants.
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PMID:Starch digestion and absorption in nonruminants. 172 68


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