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 complete sequence of the 6 kb cDNA and the 5' genomic structure are reported for the gene coding for the human intestinal brush border hydrolase sucrase-isomaltase. The human sucrase-isomaltase cDNA shows a high level of identity (83%) with that of the rabbit enzyme, indicating that the protein shares the same structural domains in both species. In addition to the previously reported homology with lysosomal alpha-glucosidase, the sucrase and isomaltase subunits also appear to be homologous to a yeast glucoamylase. A 14 kb human genomic clone has been isolated which includes the first three exons and the first two introns of the gene, as well as 9.5 kb 5' to the major start site of transcription. The first exon comprises 62 bp of untranslated sequence and the second starts exactly at the initiation ATG codon. Typical CAAT and TATA boxes are seen upstream of the first exon. A genetic polymorphism is described which involves a PstI site in the second intron. Southern blotting, sequencing and mRNA studies indicate that the structures of the sucrase-isomaltase gene and its mRNA are unaltered in the two human colon cancer cell lines Caco-2 and HT-29 in comparison with normal human small intestine.
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PMID:Sequence of the complete cDNA and the 5' structure of the human sucrase-isomaltase gene. Possible homology with a yeast glucoamylase. 135 58

The synergistic effects of dexamethasone (DEX) and thyroxine (T4) on the postnatal maturation of the 13-d-old rodent small intestine has been studied. Previous studies have shown that hydrocortisone and T4 produced a synergistic response in enzyme maturation. However, T4 elevates corticosteroid-binding globulin, which reduces the clearance of hydrocortisone. Thus, the apparent synergy between T4 and hydrocortisone may have been due to increased glucocorticoid availability. DEX, which does not bind to corticosteroid-binding globulin, was given (d8-12) at 25 pmol (i.e. 0.01 micrograms)/g body wt/d as established by a dose-response study in which this dose of DEX induced one third the maximum response in sucrase activity. In this way, synergy with T4 (130 pmol/g body wt/d, i.e. 0.1 micrograms/g body wt/d, d 5-12) could still be observed. Glucoamylase, lactase, acid beta-galactosidase, alkaline phosphatase, and sucrase activities were determined in two regions of the small intestine. Overall, the results for the two hormones administered alone showed intestinal maturation to be not significantly affected in the T4 group and partially stimulated in the DEX group. When combined, DEX + T4 synergistically increased jejunal sucrase, ileal glucoamylase, and duodenal alkaline phosphatase, and lowered ileal acid beta-galactosidase. The striking exceptions to the general pattern were two brush border enzymes that normally decline during intestinal maturation, namely ileal alkaline phosphatase and jejunal and ileal lactase. For these enzymes, DEX alone did not elicit precocious maturation, and there was no evidence for a synergistic interaction of these two hormones. Serum corticosterone concentrations also were measured. When corticosterone concentrations were compared with enzyme activity, no correlation was found.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Synergistic effects of thyroxine and dexamethasone on enzyme ontogeny in rat small intestine. 140 67

Brush border lactase, sucrase and glucoamylase activities were assessed in jejunal mucosal biopsy specimens from 34 children (median age 11 months; range 1.5-38) having protracted diarrhoea with failure to thrive and 8 well nourished children with normal jejunal mucosal histology (median age 10.2 months; range 2-37). All enzymes showed progressive decrease in activity which was directly in relation to increasing degree of mucosal injury (P less than 0.002). Lactase was significantly reduced even in patients with protracted diarrhoea and normal mucosa (P less than 0.05). Glucoamylase and sucrase were significantly reduced only in the presence of mucosal injury (P less than 0.01). Our data suggest that most children with protracted diarrhoea may not tolerate lactose containing feeds and may need lactose-free diets preferably based on starch. A small number of children with protracted diarrhoea, who have severe mucosal injury may not be able to handle even starch and may require diets based on short chain glucose polymers. The findings of this study, need to be corroborated with well-controlled metabolic balance studies.
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PMID:Intestinal glucoamylase & other disaccharidases in children with protracted diarrhoea. 211 15

The morphological maturation and the distribution of brush border hydrolase activities were studied in the small intestine and the colon in newborn babies of 28-38 weeks gestational age. Lactase and sucrase activities were higher at term with maximal activity in the proximal intestine. In contrast, aminopeptidase and glucoamylase exhibited maximum activity in the distal part of the small bowel. Glucoamylase activity was already significant in the small intestine and in the colon of the preterm newborn. Sucrase activity present in the proximal colon of the preterm dropped to a negligible amount at term, whereas aminopeptidase activity increased, reaching values found in the small intestine. The enzymic changes occurring in the intestinal tract were related to the morphological maturation of the mucosa from fetal to adult type during late gestation. Accelerated morphological and functional maturation was observed in one preterm infant nourished intravenously for 12 days, these processes being independent of the presence of nutrients in the intestine. At term, the distal part of the intestine seems to have increased digestive capacities for peptides and polysaccharides. We present evidence that full-term, and to a lesser extent preterm infants are able to hydrolyse glucose polymers.
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PMID:Longitudinal distribution of brush border hydrolases and morphological maturation in the intestine of the preterm infant. 308 71

Studies of intestinal enzyme development and regulation relevant to the human infant require an animal model with a rate of maturation similar to that of the human infant. Hanford miniature pigs were weaned at 3 days of age to a standard swine weaning formula. At 1, 2, 3, 4, 5, and 6 wk of age, duodenal jejunal, and ileal segments were analyzed for protein content and lactase, sucrase, maltase, glucoamylase, and acid beta-galactosidase activities. Protein content of the small intestine changed significantly with age only in the ileum (p less than 0.05). Lactase activity fell significantly with age in all segments of the small intestine (p less than 0.001); activity was highest in the jejunum. Sucrase and maltase activities were present in all segments of the small intestine at 1 wk of age. Sucrase increased significantly (2-fold, p less than 0.02) with age only in the ileum and maltase increased significantly with age in the jejunum (by 50%, p less than 0.05) and the ileum (3-fold, p less than 0.001). Activities were highest in the jejunum. Glucoamylase activity was present at 1 wk of age and showed a small but significant increase with age only in the duodenum (p less than 0.005). Acid beta-galactosidase activity demonstrated small but significant decreases with age in all small intestinal segments. Glucoamylase and acid beta-galactosidase activities were similar in all segments. In the 6-wk-old pigs, activities of all the enzymes tested were similar to those found in young human infants.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:The miniature pig as an animal model for the study of intestinal enzyme development. 312 4

Intestinal morphology and brush border hydrolase activities were determined along the small intestine of young adult (three months, n = 10), mature (12 months, n = 10), and senescent (29 months, n = 15) rats. The intestinal segments of the senescent rats contained higher mucosal mass and protein content (p less than 0.05) compared with the young and mature animals. A significant reduction of villus height and crypt depth (p less than 0.05) was found in the proximal intestine during aging. A 35% increase in villus height (p less than 0.05) without changes in crypt depth, was observed in the distal ileum in senescent rats. The activities of sucrase and isomaltase were significantly increased during aging in the duodenum and jejunum (p less than 0.05). Lactase and aminopeptidase activities which showed only minor changes between young and mature animals were significantly enhanced in senescent animals (p less than 0.05) with aminopeptidase exhibiting a three-fold increase in activity in the proximal ileum. The results when combined with those of previous studies suggest that in the aged animal, the increased level of intestinal hydrolase activities may be the consequence of prolonged cellular maturation along the villi in the proximal intestine, and of adaptation to increased concentrations of intraluminal substrates in the distal intestine.
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PMID:Age related increase of brush border enzyme activities along the small intestine. 320 13

Sucrase-isomaltase (S-I) and maltase-glucoamylase (M-G) of the brush border have been purified to electrophoretic homogeneity from the pigeon small intestine. Heat-inactivated enzymes of crude homogenates of the pigeon intestinal mucosa, papain-solubilized enzymes and those obtained after chromatographic fractionation behaved in an identical manner. Depending on their sensitivity to heat treatment, the disaccharidases were identified to consist of two maltases; one, the heat-labile maltase, and the other, the heat-stable maltase. Sucrase and isomaltase constituted the thermolabile maltase and could be distinguished from each other. Maltase and glucoamylase formed the thermostable maltase the activities of which however, remained inseparable. Based on these results and in accordance with the nomenclature suggested by Dahlqvist & Telenius (1969), the pigeon intestinal disaccharidases were classified as follows: Maltase Ia = isomaltase, Maltase Ib = sucrase, and Maltase II = glucoamylase. DEAE-Cellulose chromatography did not resolve the two enzyme complexes but gel filtration of the active fractions recovered from the former step, resulted in their separation into two distinct peaks. Sucrase, isomaltase and a part of the maltase activity were recovered in the first peak which eluted close to the void volume. Glucoamylase and the remaining maltase activity were recovered in the second peak which appeared to have been retarded on the column because they were eluted much more slowly. The S-I and M-G complexes have an apparent molecular weight of 195 kd and 209 kd as determined by their gel-filtration pattern on Sepharose 6B. S-I hydrolysed alpha-glucosides such as maltose, sucrose and palatinose with a Km of 3.12 mM, 8 mM and 8.36 mM respectively and did not attack starch or dextran. In contrast, M-G catalysed the hydrolysis of starch, amylose and maltose with a Km of 3.12 mM, 7.59 mM and 3.52 mM respectively, and had no action on sucrose or palatinose. Both S-I and M-G were glycoproteins, and were inhibited by Ag+, Hg2+ and Tris but not by p-hydroxymercuribenzoate, iodoacetamide or imidazole. Na+ on the other hand activated both the enzyme complexes by about 20-25%. It is suggested that the molecular and catalytic properties of intestinal disaccharidases of pigeons do not differ considerably from those of Mammals.
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PMID:Studies on the intestinal disaccharidases of the pigeon. III. Separation, purification and properties of sucrase-isomaltase and maltase-glucoamylase. 620 6

The present study was designed to investigate the effects of grape seed tannins on rat intestinal alkaline phosphatase (AP), sucrase and dipeptidyl peptidase IV (DPP IV) activities. An experiment was performed in vivo by dietary supplementation with 2% tannins; this diet was tested on an experimental group of rats; a control group received a diet without tannins. After 31 days, tannins intake significantly decreased middle-jejunal AP from 123 to 45 mU/mg protein and sucrase activities from 310 to 195 mU/mg protein, while no significant difference appeared at the duodenal stage (p < 0.05). Ileal DPP IV activity was also significantly reduced (p < 0.05) from 190 to 110 mU/mg protein after tannin intake. Using in vitro experiments on purified brush border membranes, AP activity was found to be inhibited by grape tannins; this inhibition was prevented by the detergent Triton X-100. The addition of pancreatic-biliary (PB) juice to the incubation medium prevented or reversed the tannin-inhibited enzyme activity. The present data indicate that in the duodenal lumen, alkalinity and detergency from the PB secretion neutralized the ability of tannins to inactivate brush border hydrolase activities and suggest that enzyme inhibition took place once bile salts were reabsorbed while moving down the gut. This was confirmed by in vitro experiments where sucrase and DPP IV activities inhibited by grape seed tannins were largely recovered after the addition of PB juice to the incubation medium.
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PMID:Effect of grape seed tannins on the activity of some rat intestinal enzyme activities. 778 71

To determine the prevalence of short polymers of glucose and starch malabsorption caused by small intestinal glucoamylase deficiency in children with chronic diarrhea, we studied small bowel biopsy specimens from 511 children (aged 1 month to 9 years) with chronic diarrhea evaluated at 54 medical centers. Glucoamylase and disaccharidase (lactase, sucrase, maltase, and palatinase) enzyme assays were performed. Of the 511 children, 15 had glucoamylase deficiency. Six who had significant small intestinal mucosal injury and disaccharidase deficiencies were defined as having secondary glucoamylase deficiency; the other nine patients with normal mucosal morphologic features were defined as having primary glucoamylase deficiency. Secretin tests showed normal pancreatic amylase values for age in all seven children tested. Four of them had abnormal findings on tolerance tests for starch and short polymers of glucose (rise in blood glucose concentration: < 20 mg/dl) and reducing substances in stools, and three of these four had symptoms of intolerance (abdominal distention, flatulence, and diarrhea). All seven patients responded to a starch elimination diet. After reintroduction of a starch diet, diarrhea recurred in four patients; this was alleviated 48 hours after reelimination of starch. We conclude that intestinal glucoamylase deficiency is present in some patients with chronic diarrhea.
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PMID:Small intestinal glucoamylase deficiency and starch malabsorption: a newly recognized alpha-glucosidase deficiency in children. 815 67

In this paper we report the expression in Pichia pastoris, purification, and characterization of the Aspergillus awamori glucoamylase catalytical domain (GAc). Pichia pastoris produced GAc to the level of 0.4 g per liter medium. This production level is about the same level as that gained for recombinant GA from Aspergillus and about 100-fold more than previously achieved by Saccharomyces cerevisiae. The GAc expressed in Pichia pastoris was purified by two independent chromatographic methods employing ion exchange or affinity chromatography to apparent homogeneity. The purified protein has a molecular weight of about 75,000 and specific activity of 78 units per milligram protein. The propeptide present in the glucoamylase N terminus was found to be removed correctly by P. pastoris. Glucoamylase produced by P. pastoris is N- and O-glycosylated, with 23% carbohydrate content. The N-linked oligosaccharides appear to be larger than in invertase, another glycoprotein heterologously expressed in P. pastoris. O-glycosides (studied to our knowledge for the first time in P. pastoris in this report) contribute about half of the total carbohydrate content in GAc. Purified GAc appears as multiple hands on isoelectric focusing with p1 values around 3.5, a value that is little higher than that for GAc produced in S. cerevisiae. GAc could be used as a versatile tool in studying protein expression in P. pastoris: as an affinity handle for other secreted proteins produced in P. pastoris, as a reporter gene when studying gene expression, and as a model protein in studying protein secretion and processing in P. pastoris.
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PMID:Expression in Pichia pastoris and purification of Aspergillus awamori glucoamylase catalytic domain. 917 93


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