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 genetically conditioned mouse model of exocrine pancreatic insufficiency (epi) has been used to study the effect of the absence of lumenal proteases on small intestinal mucosal proteins. The small bowel was divided into eight equal segments. Enzyme activity was increased only in the first three segments in the case of maltase, sucrase, and lactase (all mol wt above 200,000). Alkaline phosphatase (mol wt 145,000), trehalase (mol wt 95,000), and peptidase (mol wt 175,000) activities were unaffected in proximal segments from epi mice. Proximal brush border proteins were identified and measured quantitatively by sodium dodecyl sulfate acrylamide gel electrophoresis. Those enzymes with increased activity were associated with increased amounts of protein in epi mice. Double labeled studies of protein turnover revealed a longer half-life for large brush border proteins (mol wt above 175,000) in epi mice than in normal mice. Enterokinase activity (a marker for duodenal mucosa) was nearly absent from the duodenum of epi mice. Receptors for the intrinsic factor-vitamin B12 complex (markers for ileal mucosal) were present in the ileum equally in normal and in epi mice. Enterokinase activity can be induced in epi mice by feeding its substrate trypsinogen, but not by trypsin or chymotrypsinogen. Epi mice thus retain the ability to synthesize enterokinase. Pancreatic proteases play an important role in the turnover of certain large mucosal proteins and in the induction of enterokinase.
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PMID:Effect of exchange exocrine pancreatic insufficiency on small intestine in the mouse. 20 83

The concomitant appearance of enterokinase (EK) and trypsin activities in the human intestinal mucosa is indicative of the importance of EK as an activator of trypsinogen and therefore as the key enzyme in protein digestion. Enterokinase can be detected in fetal mucosa from the 26th week of gestation on, paralleling appearance of tryptic activity in meconium. The developmental pattern of EK activity increases with age. Between 26 to 30 weeks of gestation, the EK activity is only 6% and full term babies (40 weeks) 20% of that found in older children. In contrast, lactase studies during development show a lactase activity of only 30% in human fetuses between 26 to 34 weeks of gestation as compared to full term babies. During the same gestational period, sucrase and maltase activities reach 70% of the full term. In addition, the distributional pattern of EK differs from the disaccharidases, showing the highest activity in duodenum and the lowest in ileum, whereas disaccharidases are highest in jejunum with lower activity in duodenum and ileum. Differences in topographical distribution and time of appearance of EK and disaccharidases may be attributed to differences in orgin as well as subcellular localization of these enzymes. It is conceivable that the premature infant, between 26 to 30 weeks of gestation, is better equipped to deal with hydrolysis of alpha-glucosides than of lactose.
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PMID:Developmental pattern of small intestinal enterokinase and disaccharidase activities in the human fetus. 55 25

Intravenous administration of 1 U cholecystokinin-pancreozymin (CCK-PZ) to rats caused the release of enteropeptidase, alkaline phosphatase (AP), and sucrase to the intestinal lumen in the absence of a concomitant increase in luminal DNA. Thus, the hormone elicited hydrolase secretion was not due to cell desquamation. Pentagastrin also stimulated hydrolase release. Following CCK-PZ administration enteropeptidase was released preferentially over sucrase and AP and showed a linear correlation with total protein output. The specific enteropeptidase activity was higher in the perfusate following secretion than in the mocosa. Enteropeptidase was found mainly in soluble form in both mucosa and perfusate; addition of bile following enteropeptidase release further increased its activity. In contrast, sucrase and AP were found mainly in insoluble form in both mucosa and perfusate and their specific activities were higher in the mucosa. The presence of bile rendered both sucrase and AP more soluble in the perfusate. The data indicate that enteropeptidase is released by a specific secretory process and that its subcellular site of origin is different from that of sucrase and AP. By eliciting the coordinated release of trypsinogen, enteropeptidase and bile, CCK-PZ plays a central role in the initiation of protein digestion.
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PMID:Studies on intestinal enzyme secretion; the action of cholecystokinin-pancreozymin, pentagastrin and bile. 68 84

The results presented show striking differences in the response of the exocrine pancreas to fasting in suckling versus adult rats. In adult rats, fasting led to an increase in lipase to amylase ratio with a particularly sharp decrease in amylase concentrations, a generalized decrease in total protein, amylase, trypsinogen and lipase contents, and a decrease in responsiveness of the pancreatic acini to optimal and supraoptimal concentrations of secretagogues in vitro. In 15 day old pups, however, fasting led to an increase in total amylase, trypsin and lipase and a maintenance of the total protein content in their pancreases. Further, no decrease in responsiveness of their pancreatic acini to secretagogue stimulation is observed at the concentrations studied. The difference in the behavior of the exocrine pancreas during fasting can be partly explained by the changing pattern of their responses to hormonal stimulation, particularly that of corticosterone and cholecystokinin during various stages of development. Fasting led to an increase in corticosterone and presumable decrease in cholecystokinin. The pancreas of the suckling rat is very sensitive to the induction effect of corticosterone while that of the adult rats is relatively insensitive. Conversely, the pancreas of the adult rats is sensitive to the trophic effect of cholecystokinin while that of the suckling rat has the opposite reaction. The combination of these and other factors then resulted in an entirely different profile of the responses of the exocrine pancreas to fasting. Recent studies in our laboratory, and that of others, showed that an analogous situation also existed in the small intestine. Fasting of adult rats led to a general decrease in small intestinal enzymes including sucrase and maltase (29) but in suckling rats led to (30,31) increases of sucrase and maltase. Corticosterone again has been shown to be involved (30,31). Further, the small intestinal sucrase of the suckling rats responded to corticosterone by an increase in its level but the same hormone did not seem to control the sucrase concentrations in the small intestine of adult rats (32,33). Thus, both the small intestine and the pancreas responds very differently to fasting presumably mediated through a varying pattern of responses to selective hormonal stimulation, eg in this case, corticosterone. These results strongly suggest the importance of the interaction between environmental influences (fasting in this case) and the stage of development in determining the outcome of ontogenesis.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Response of the pancreas to fasting: adult versus neonates. 620 75

Feed efficiency in rats fed a low soybean protein isolate (SPI) diet (100 g/kg diet) was dramatically improved with the supplementation of L-methionine (3 g/kg diet). Pancreatic amylase activity was low in rats fed a low SPI diet, and was much higher in the supplemented group than in the non-supplemented group. Pancreatic trypsinogen and chymotrypsinogen contents (as activities of trypsin and chymotrypsin) were not changed with the methionine supplementation. In the small intestine, sucrase and leucine aminopeptidase in the jejunum and ileum were not clearly changed. In conclusion, a small amount of methionine supplemented to a low SPI diet especially induced pancreatic amylase among digestive enzymes. The factor involved in nutritional status, not the physiological action of methionine itself, may contribute the induction of amylase.
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PMID:Supplementation of methionine to a low soybean protein diet strikingly increases pancreatic amylase activity in rats. 915 Dec 50

We previously reported that rats receiving total parenteral nutrition (TPN) undergo significant pancreatic atrophy characterized by reduced total protein and digestive enzyme expression due to a lack of intestinal stimulation by nutrients (Baumler MD, Nelson DW, Ney DM, Groblewski GE. Am J Physiol Gastrointest Liver Physiol 292: G857-G866, 2007). Essentially identical results were recently reported in mice fed protein-free diets (Crozier SJ, D'Alecy LG, Ernst SA, Ginsburg LE, Williams JA. Gastroenterology 137: 1093-1101, 2009), provoking the question of whether reductions in pancreatic protein and digestive enzyme expression could be prevented by providing amino acids orally or by intravenous (IV) infusion while maintaining intestinal stimulation with fat and carbohydrate. Controlled studies were conducted in rats with IV catheters including orally fed/saline infusion or TPN-fed control rats compared with rats fed a protein-free diet, oral amino acid, or IV amino acid feeding, all with oral carbohydrate and fat. Interestingly, neither oral nor IV amino acids were sufficient to prevent the pancreatic atrophy seen for TPN controls or protein-free diets. Oral and IV amino acids partially attenuated the 75-90% reductions in pancreatic amylase and trypsinogen expression; however, values remained 50% lower than orally fed control rats. Lipase expression was more modestly reduced by a lack of dietary protein but did respond to IV amino acids. In comparison, chymotrypsinogen expression was induced nearly twofold in TPN animals but was not altered in other experimental groups compared with oral control animals. In contrast to pancreas, protein-free diets had no detectable effects on jejunal mucosal villus height, total mass, protein, DNA, or sucrase activity. These data underscore that, in the rat, intact dietary protein is essential in maintaining pancreatic growth and digestive enzyme adaptation but has surprisingly little effect on small intestinal mucosa.
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PMID:Intravenous or luminal amino acids are insufficient to maintain pancreatic growth and digestive enzyme expression in the absence of intact dietary protein. 2053 7