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)

1. Trehalase, sucrase-isomaltase and maltase-glucoamylase are three integral glycoproteins of the brush border membranes of the enterocytes. On the basis of a comparative study on alpha-glycosidase activities (sucrase, isomaltase, maltase, glucoamylase and trehalase) associated to these glycoproteins during neonatal development, mammals could be basically divided into three groups. 2. In rodents and rabbit alpha-glycosidase activities are low or undetectable during the suckling period and increase to adult levels during the weaning period. In cat, dog and the primates examined, alpha-glycosidase activities are well or fully developed at birth. 3. In ruminants and pinnipedia alpha-glycosidases are low or absent throughout life. 4. During the suckling period of rat, mouse and rabbit, glucocorticoids trigger a premature and dramatic increase of all alpha-glycosidases. 5. On the contrary, alpha-glycosidases development during the weaning period appears to be independent of glucocorticoids. Neither hypophysectomy nor adrenalectomy prevent the development of alpha-glycosidases; only the rate of increase is reduced. 6. Transplantations of intestinal isografts either in adult or suckling animal, have shown that (1) no systemic factor inhibits the expression of alpha-glycosidase, (2) alpha-glycosidases induction is neither triggered by luminal alimentary substances, nor by hormones, (3) alpha-glycosidase development is controlled by an intrinsic ontogenic program. 7. The use of an antiglucocorticoid failed to inhibit the spontaneous development of alpha-glycosidase activities. 8. The increase of maltase and sucrase activities triggered by glucocorticoids is associated with an increase of the concentration of two glycoproteins in the microvillous membrane: sucrase-isomaltase and maltase-glucoamylase. 9. After administration of glucocorticoids the increase of maltase, sucrase and trehalase is strongly inhibited by actinomycin-D and the increase of sucrase activity is associated with a parallel increase of sucrase-isomaltase mRNA. Transcription is most likely the primary site of control of alpha-glycosidase biosynthesis. 10. In the crypt cells, alpha-glycosidases biosynthesis appears to be triggered by a receptor-mediated glucocorticoid interaction. 11. The enterocytes synthesize more alpha-glycosidase molecules as they travel to the tip of the villi. 12. The simultaneous, biosynthesis of sucrase-isomaltase and maltase-glucoamylase triggered by glucocorticoids, as well as their simultaneous normal development suggest that they may be subjected to related control mechanisms. 13. It is suggested that sucrase-isomaltase and maltase-glucoamylase might have arisen by several cycles of partial gene duplication of an ancestor gene coding for a single site maltase-isomaltase; subsequent mutation would have transformed isomaltase into sucrase or glucoamylase.
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PMID:Brush border membrane sucrase-isomaltase, maltase-glucoamylase and trehalase in mammals. Comparative development, effects of glucocorticoids, molecular mechanisms, and phylogenetic implications. 251 62

Maturation of mechanisms for carbohydrate absorption occurs in a defined sequence during human fetal development. The intestinal enzymes, lactase, sucrase, maltase, isomaltase, and glucoamylase, are at mature levels in the term fetus. Mature levels of pancreatic amylase activity and glucose transport occur postnatally, and levels are low in both the term and preterm neonate. In the preterm infant, sucrase, maltase, and isomaltase are usually fully active, but lactase activity, which increases markedly from 24 to 40 weeks, may be low depending upon fetal age. Despite these developmental patterns, clinical lactose intolerance is uncommon. Postnatal adaptive responses to ingested carbohydrates lead to competent carbohydrate absorption. Inadequately absorbed carbohydrates are salvaged by colonic flora through fermentation of carbohydrates to hydrogen gas and short-chain fatty acids; the latter are readily absorbed by the colon. In this setting, carbohydrate tends to be absent from the stool. Noninvasive reflection of the status of carbohydrate absorption may be obtained from breath hydrogen testing, a technique of particular value in young infants.
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PMID:Development of carbohydrate absorption in the fetus and neonate. 257 23

We describe a new and unique gastric carcinoma cell line (LIM1839) derived from a young Caucasian male with rapidly progressing disease. The cell line grows with a pleomorphic morphology and has been in continuous culture for more than 3 years. The cells cannot be cloned in semi-solid agar or grown in nude mice despite numerous attempts. The karyotype of the cultured cells is highly abnormal with a large number of structural and numerical changes. Some chromosomes are dicentric and this feature has persisted in this culture. The cells express one of the small-intestinal dipeptidases, aminopeptidase N, but do not express dipeptidyl peptidase IV or the disaccharidases, sucrase isomaltase or maltase glucoamylase. The cells express high levels of EGF receptors and of messenger RNA for insulin-like growth factor II.
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PMID:A new gastric carcinoma cell line (LIM1839) derived from a young Caucasian male. 260 77

Castanospermine-glucosides (CS-glcs) are new compounds which have been evaluated as glycohydrolase inhibitors in rats. 7-O-alpha-D-Glucopyranosyl-CS (7 alpha-glc-CS) and 8 alpha-glc-CS were potent sucrase inhibitors with IC50s of 40 and 30 nM, respectively. Their sucrase inhibition was poorly reversible. They were much weaker liver lysosomal alpha-glucosidase inhibitors with IC50s of 40,000 nM. 1 alpha-glc-CS and 8 beta-glc-CS were both weaker and less selective sucrase inhibitors. In vivo, 7 alpha-glc-CS and 8 alpha-glc-CS effectively reduced the glycemic response to an oral 2 g/kg sucrose load at doses less than or equal to 1 mg/kg. 8 alpha-glc-CS was effective when administered up to 4 hr before sucrose. The known glucohydrolase inhibitors 1-deoxynojirimycin and N-hydroxyethyl-1-deoxy-nojirimycin were also potent sucrase inhibitors (IC50s = 200 and 400 nM, respectively) but their sucrase inhibition was readily reversible in vitro and their in vivo duration of action was much shorter than for the CS-glcs. Among the glucohydrolase inhibitors tested, the prolonged in vivo duration of action could be predicted by poor reversibility from sucrase. These CS-glcs provide a new generation of sucrase inhibitors which may be useful in the treatment of diabetes mellitus.
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PMID:Castanospermine-glucosides are potent, selective, long-acting sucrase inhibitors. 267 17

The fetal and postnatal activity patterns of different hydrolytic enzymes (alkaline phosphatase, gamma-glutamyltransferase, trehalase, maltase, glucoamylase, lactase, and sucrase) have been examined in mouse renal homogenates. Alkaline phosphatase and gamma-glutamyltransferase activities presented approximately similar changes. They increased from 18 days of gestation up to 30 days after birth. These activities showed marked increases during the 3rd and 4th postnatal weeks. A similar important rise was observed for trehalase activity at the end of the suckling period. Maltase activity increased gradually after birth. Traces of lactase, sucrase, and glucoamylase activities were detected at each developmental stage.
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PMID:[Activity of renal hydrolases in pre- and postnatal development of mice]. 286 26

The inhibitory action and mechanism of inhibition of two types of alpha-glucosidase inhibitors, acarbose (Bay-g-5421) and 1-deoxynojirimycin derivatives (Bay-m-1099 and Bay-o-1248), on small intestinal carbohydrases (sucrase, isomaltase, glucoamylase, trehalase and lactase) and pancreatic alpha-amylase were compared in vitro using small intestinal brush border membranes and pancreatic homogenates from adult Sprague-Dawley rats. Acarbose at a low (4 microM) concentration strongly inhibited the activities of glucoamylase, alpha-amylase and sucrase (98, 68, and 63%, respectively). At a high (200 microM) concentration, isomaltase activity was also inhibited (28%); effects on trehalase and lactase activities were negligible. Both the 1-deoxynojirimycin derivatives were even more potent inhibitors of sucrase (Ki = 8.6 x 10(-8) M for Bay-m-1099;Ki = 5.0 X 10(-8) M for Bay-o-1248) than acarbose (Ki = 9.9 x 10(-7) M). Whereas glucoamylase activity was strongly inhibited by the 1-deoxynojirimycin derivatives, alpha-amylase activity was not. In contrast to acarbose, the 1-deoxynojirimycin derivatives at high concentrations (20-200 microM) inhibited considerably trehalase and lactase (a beta-galactosidase) activities. The inhibition of lactase activity was stronger by Bay-m-1099 (Ki = 4.9 X 10(-6) M) than by Bay-o-1248 (Ki = 6.7 X 10(-5) M). Where inhibition was seen, kinetic analysis showed fully competitive inhibition of sucrase, isomaltase, trehalase, glucoamylase and lactase by all three inhibitors.
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PMID:Inhibitory mechanism of acarbose and 1-deoxynojirimycin derivatives on carbohydrases in rat small intestine. 296 44

Lysosomal alpha-glucosidase (acid maltase) is essential for degradation of glycogen in lysosomes. Enzyme deficiency results in glycogenosis type II. The amino acid sequence of the entire enzyme was derived from the nucleotide sequence of cloned cDNA. The cDNA comprises 3636 nt, and hybridizes with a messenger RNA of approximately 3.6 kb, which is absent in fibroblasts of two patients with glycogenosis type II. The encoded protein has a molecular mass of 104.645 kd and starts with a signal peptide. Sites of proteolytic processing are established by identification of N-terminal amino acid sequences of the 110-kd precursor, and the 76-kd and 70-kd mature forms of the enzyme encoded by the cDNA. Interestingly, both amino-terminal and carboxy-terminal processing occurs. Sites of sugar-chain attachment are proposed. A remarkable homology is observed between this soluble lysosomal alpha-glucosidase and the membrane-bound intestinal brush border sucrase-isomaltase enzyme complex. It is proposed that these enzymes are derived from the same ancestral gene. Around the putative active site of sucrase and isomaltase, 10 out of 13 amino acids are identical to the corresponding amino acids of lysosomal alpha-glucosidase. This strongly suggests that the aspartic acid residue at this position is essential for catalytic function of lysosomal alpha-glucosidase.
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PMID:Primary structure and processing of lysosomal alpha-glucosidase; homology with the intestinal sucrase-isomaltase complex. 304 72

In investigations on the intracellular transport route(s) of lysosomal enzymes in polarized epithelial cells, we used immunocytochemical methods to localize lysosomal alpha-glucosidase in human small-intestinal epithelial cells. Two monoclonal antibodies which can discriminate between different biosynthetic forms of this enzyme were used. One monoclonal antibody, 43D1, which recognizes all forms of the enzyme, showed labeling of the Golgi apparatus, the lysosomes and, unexpectedly, of the brush border of the cells. Multivesicular bodies were free of label. In contrast, monoclonal antibody 43G8, which recognizes all forms except the 110,000 Da precursor of alpha-glucosidase, showed labeling of the lysosomes only. This leads us to conclude that the 110,000 Da precursor form of alpha-glucosidase is present in the Golgi apparatus and the brush border of human small-intestinal epithelial cells. Moreover, biochemical experiments show that this precursor copurifies with sucrase, a typical brush-border marker, when a partially purified microvilli fraction is prepared.
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PMID:Immunocytochemical demonstration of the lysosomal enzyme alpha-glucosidase in the brush border of human intestinal epithelial cells. 306 58

Animal experimentation with total parenteral nutrition (TPN) has revealed the occurrence of atrophy of the intestinal mucosa and decreased enzyme activities of the brush border, notably the disaccharidases. These findings have heretofore not been confirmed in human investigation. We performed endoscopic biopsies in the third part of the duodenum in 7 adults before TPN, after 21 days of TPN, and after a progressive oral refeeding. We noted a clear-cut decrease of major enzyme activities during TPN (sucrase, maltase, lactase, glucoamylase, acid aminopeptidase, dipeptidyl peptidase) without any morphologic modifications as observed with standard histology. Electron microscopy showed a slight but significant decrease in the height of microvilli. The decreased enzyme activities were rapidly restored after oral refeeding. Thus, the functional consequences of the modifications observed during medium-term TPN in adults are probably limited.
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PMID:Decreased brush border hydrolase activities without gross morphologic changes in human intestinal mucosa after prolonged total parenteral nutrition of adults. 307 17

Hydrocortisone administration to infant rats enhanced cellobiase and maltase activities and induced precocious expression of sucrase and trehalase activities along the length of the small intestine. These activity changes reflected proportional concentration increases in the enzymes lactase (EC 3.2.1.23), maltase/glucoamylase (EC 3.2.1.20) and sucrase-isomaltase (EC 3.2.1.48/10). Administration of an equivalent tracer dose of [3H]leucine (by body weight) to control and hydrocortisone-treated infant rats resulted in greater accumulation of label in the carbohydrase pools of the treated rats, suggesting their increased de novo synthesis. The increased concentrations of lactase and maltase/glucoamylase induced by exogenous hydrocortisone were matched by the presence of corresponding greater amounts of label in their brush border pools. Accumulation of label in each of the lactase, maltase/glucoamylase and sucrase-isomaltase pools was generally similar in the hydrocortisone-treated rats, suggesting equivalent stimulation of their synthesis as a group by the humoral agent. The turnover rates of the carbohydrases as a group were found to be similar and did not appear to differ in control and hydrocortisone-treated rats. Total protein synthesis rates were slightly greater in the intestine of the hydrocortisone-treated group of rats.
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PMID:Effects of hydrocortisone on carbohydrase concentrations, de novo synthesis and turnover patterns in immature rat intestine. 308 73


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