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:3.4.21.4 (trypsin)
42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Enterokinase is an enzyme produced by the mucosa of the small intestine. Its sole function is to activate trypsinogen to trypsin. In animals and man the duodenum and proximal jejunum have high levels of activity whereas the remaining small bowel has minimal levels. A reproducible assay was developed for measuring mucosal enterokinase activity applicable to operative and endoscopic biopsies. Anaesthetic and operative techniques were developed for small intestinal resections in guinea-pigs to ensure their long term survival. Transposition of high-enterokinase-secreting segments of guinea-pig small intestine to low-enterokinase regions and vice versa showed no alteration of enterokinase activity in the transposed segments. Similarly, resection of the enterokinase region in five proximal pancreaticoduodenectomy operations in man revealed no induction of enterokinase in the remaining jejunum at endoscopy 6 months later. Isolation of high-enterokinase-secreting segments of small bowel from their luminal continuity by fashioning of Thiry--Vella fistulas led to a decay of enterokinase activity to minimal levels within 12--16 h. Perfusion of these fistulas with trypsin and sodium, or chymotrypsin and sodium, prevented this decay. If the enterokinase was allowed to decay over 24 h its activity could be restored to 80 per cent of its normal level by perfusion for 24 h with trypsin and sodium. Trypsin and sodium acti in combination on an enterocyte membrane receptor to stimulate enterokinase synthesis.
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PMID:Regulation of enterokinase synthesis in animal and human small intestine by luminal signals: its implication in upper gastrointestinal surgery. 50 46

The potato inhibitors of proteases inhibit the activation of trypsinogen, chymotrypsinogen, proelastase, procarboxypeptidase A and B induced by trypsin. These inhibitors do not inhibit the activation of trypsinogen induced by enterokinase. Potato inhibitors have no influence on pepsinogen autoactivation and on pepsin activity.
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PMID:The action of potato inhibitors on activation of zymogen forms of digestive system proteases. 52 19

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

After 48 h of bile duct ligation, enterokinase activity in rat mucosa was significantly lowered in comparison with controls or rats with bile fistula. Rats with bile fistula were similar to controls. Sucrase levels were similar in all groups. Without endogenous trypsinogen, duodenal perfusion with a trypsinogen-containing solution led to more conversion to trypsin by controls. When their own pancreatic secretion was the source of trypsinogen, trypsin was much higher in perfusate from bile-ligated rats. Solubilized enterokinase was also higher in this group. These results indicate that bile stasis leads to decreased mucosal enterokinase activity and increased pancreatic function. The latter may have caused accelerated loss of enterokinase into the lumen, leading to lower mucosal levels.
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PMID:Influence of biliary stasis on enterokinase activity in the rat. 75 Feb 64

Bovine enterokinase was purified from duodenal mucosa. The purification included an initial extraction with 2% deoxycholate, ammonium sulfate fractionations, DEAE-cellulose chromatography, and affinity chromatography on basic pancreatic trypsin inhibitor (Kunitz) (PTI)-Sepharose. The purified enzyme contained 35% carbohydrate; it had a molecular weight of 150,000, with a heavy (115,000) and light (35,000) chain connected by one or more disulfide bonds. Enterokinase hydrolyzed lysine and arginine substrates and slowly reacted with the trypsin active site titrant 4-methylumbelliferyl-p-guanidinobenzoate. The enzyme activated bovine trypsinogen with kinetic parameters similar to those of other preparations of enterokinase. Bovine enterokinase was inhibited by Kunitz pancreatic trypsin inhibitor with a Kassoc of 2 X 10(8) M-1 and only weakly by other proteinase inhibitors. The amino acid composition differed from bovine enterokinase isolated from duodenal contents (Anderson, L.E., Walsh, K.A., and Neurath, H. (1977) Biochemistry 16, 3354-3360). The mucosal enzyme and the duodenal contents enzymes also differed in the size of the heavy and light chains. The mucosal enterokinase more closely resembled the properties of porcine enterokinase (Baratti, J., Maroux, S., Louvard, D., and Desnuelle, P. (1973) Biochim. Biophys. Acta 315, 147-161). The amino acid composition and size of the light chain were also similar to bovine trypsin.
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PMID:The preparation and properties of bovine enterokinase. 76 66

The various peptidases secreted by such exocrine tissues as gastric mucosa, pancreas and prostate are usually determined by catalytic methods. Another approach utilizes immunoassay. Endopeptidases were formerly assayed with protein substrates such as hemoglobin and albumin. These techniques are increasingly replaced by more specific ones using artificial peptide derivatives as substrates, some of which allow an increase in absorbance or fluorescence to be continuously recorded. The presently available methods of assaying pepsin, pancreatic trypsin, trypsinogen and carboxypeptidase A, enterokinase and several peptidases of human sperm are reviewed.
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PMID:The assay of exocrinous peptidases in clinical chemistry. 77 94

Enterokinase initiates digestion of protein by conversion of trypsinogen into trypsin. The interactions between enterokinase and trysin were investigated in 6 patients with intractable diarrhea of infancy and 34 children with celiac disease. The six infants between 2 and 3 months with intractable diarrhea of infancy had reduced mucosal enterokinase activity (9.5 +/- 4.8muM per gram of protein per minute) and reduced intraluminal trypsin activity (2.9 +/- 0.7muM per gram of protein per minute) as compared with healthy controls (109 +/- 34.2muM per gram of protein per minute and 14.3 +/- 5.8muM per gram of protein per minute) respectively. The activities of all enzymes returned toward normal following treatment with intravenous alimentation. The mucosal morphology of all pretreatment biopsies in all cases showed Grade III atrophy which improved. These findings suggest that enterokinase deficiency and reduced intraluminal trypsin activity in intractable diarrhea of infancy may be one of the contributing factors to protein malabsorption and consequent malnutrition. Thirty-four children with celiac disease were between the age of 9 months and 13 years. The 11 newly diagnosed patients with celiac disease demonstrated Grade III to IV atrophy of the mucosa. The 23 patients with treated celiac disease on a gluten-free diet showed a normal to Grade II atrophy. In both treated and untreated celiac disease the enterokinase activities and the intraluminal trypsin activity were within normal limits. The enterokinase activity in celiac disease is near normal in contrast to the marked reduction noted in intractable diarrhea of infancy even though the intestinal mucosa shows marked morphological alteration and the disaccharidase activities are greatly reduced in celiac disease. After a prolonged alimentary fast of up to 26 days on intravenous alimentation, two patients with intractable diarrhea of infancy showed improvement in the activities of enterokinase and trypsin. These findings demonstrate that enterokinase and trypsin activities in the gut were present and improved in the absence of oral feeding.
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PMID:The interrelationship of enterokinase and trypsin activities in intractable diarrhea of infancy, celiac disease, and intravenous alimentation. 80 41

In rats fed equal amounts of isocaloric high-protein (HPR) and low-protein (LPR) diets, studies were performed on the mucosal activities of enterokinase and alkaline phosphatase and on the activities of these enzymes and of trypsin in washings obtained from the contents of two standard 5 cm. segments of duodenum, located proximal (Segment I) and distal (Segment II) to the main pancreatic duct. Mean mucosal weights and tissue protein per segment were 1.3-fold higher in rats fed HPR diets. In Segment I, but not Segment II, mucosal activities per segment were higher in HPR for enterkinase (threefold) and alkaline phosphatase (twofold). In luminal washings trypsin did not differ between the two groups; in HPR luminal levels of enterkinase were significantly higher in Segment II and those of alkaline phosphatase were similarly elevated in Segment I. Irrespective of diet the major activity of both enzymes was in mucosal fractions. Studies of total activity of each enzyme showed that the enzymes behave rather similarly, with the major differences between the dietary groups discernible in Segment I. These data stress the importance of dietary protein content in intestinal enzyme adaptation and reveal regional variation in the responses of the different enzymes.
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PMID:Alterations in enterkinase, trypsin, and alkaline phosphatase in response to variation in dietary protein content in the rat. 83 Jul 83

Experimental pancreatitis (PT) is induced by proximal and distal duodenal closure in the bile-duct-ligated dog, by causing duodeno-pancreatic reflux of lumenal secretions. It has been postulated that trypsin and enterokinase (EK) in the secretions activate trypsinogen within the pancreas, producing PT. There is supporting evidence for trypsin, but EK has not previously been investigated. To determine whether EK alone could cause PT, we injected saline suspensions of partially purified EK, and other test materials, into the duct of Wirsung of dogs and after 24 hr examined their pancreases and estimated the increment in serum amylase. Following 0.5% EK, both PT and hyperamylasemia (HA) ensued; HA without PT occured when EK was inactivated by heat, administered with trypsin inhibitor (TI), or administered in more dilute solution. Injection of TI or of hog gastric mucin likewise leads to HA but not to PT. It is concluded that the PT observed was due to EK activity, and that therefore EK could contribute to the production of PT observed was due to EK activity, and that therefore EK could contribute to the production of PT in the closed-duodenal-loop model. The HA observed in the absence of PT is unexplained but appears to be related to the colloidal properties of the materials injected.
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PMID:Pancreatitis following the intraductal injection of partially purified enterokinase in dogs. 84 25

The purification and characterization of three pancreatic trypsinogens A1, A2, and A3, from the African lungfish, Protopterus aethiopicus, is reported. These zymogens are activated by trypsin, by enterokinase, by an acid protease from Aspergillus oryzae, and by autoactivation. The three trypsinogens contain the same amino-terminal amino acid sequence, beginning with the activation peptide Leu-Pro-Leu-Glu-Asp-Asp-Lys-. Like the activation peptide of the previously characterized trypsinogen B [Reeck, G. R., & Neurath, H. (1972) Biochemistry 11, 503] of the same organism, it lacks the tetraaspartyl sequence characteristic of other vertebrate trypsinogens. Two of the corresponding lungfish trypsins were found to have identical amino-terminal sequences for at least 27 residues. These data suggest that the three enzymes are allelic variants. In contrast, the amino acid sequences differ sufficiently from that of trypsinogen B of the same organism to indicate that trypsinogens A and B are the products of different gene loci.
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PMID:Isolation and amino-terminal sequence analysis of a new pancreatic trypsinogen of the African lungfish Protopterus aethiopicus. 91 66


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