Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.9 (enterokinase)
 675 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

Rat pancreatic juice (RPJ) reduced the mean uptake of 57CoB12 bound to rat intrinsic factor (IF) by perfused rat intestinal segments from 30.1 +/- 2.4 (pg 57CoB12 per cm intestine +/- S.E.M.) to 26.7 +/- 2.4 (p less than 0.05). RPJ activated with enterokinase reduced the uptake from 22.8 +/- 2.8 to 16.1 +/- 1.9 (p less than 0.05). RPJ also reduced the uptake from 15.8 +/- 2.3 to 8.3 +/- 2.0 (p less than 0.01) in segments from partially pancreatectomized rats. Rat bile abolished the inhibitory effect of RPJ. The results indicate that in the absence of bile the exocrine pancreatic secretion is capable of inhibiting the intestinal uptake of vitamin B12.
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PMID:Inhibitory effect of pancreatic juice on the intestinal uptake of vitamin B12. 99 36

Although pancreatic enzymes clearly degrade R binder, a nonintrinsic factor binder, the full scope of the pancreatic role in cobalamin absorption remains the subject of debate. Therefore the direct effect of pure human pancreatic juice (PPJ) on ileal cobalamin absorption in the absence of intrinsic factor was studied. PPJ significantly enhanced cobalamin uptake in guinea pig ileal loop perfused in vivo. It did not do so in the jejunum. This PPJ activity in the ileum was further stimulated by enteropeptidase and inhibited by aprotinin. The intestinal mucosa remained intact during our study by morphologic and inulin clearance criteria and behaved normally with respect to intrinsic factor and nonintrinsic factor binders. Since no intrinsic factor was present in the perfusate, PPJ must directly enhance cobalamin uptake by the ileum, perhaps promoting cobalamin attachment to receptor sites for subsequent transport by intrinsic factor. PPJ thus seems to affect cobalamin absorption at several levels. Previous studies have established its interaction with luminal R binders and with bile. The findings now indicate that pancreatic juice may have an additional, more direct role in promoting cobalamin absorption in the ileum.
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PMID:Pure human pancreatic juice directly enhances uptake of cobalamin by guinea pig ileum in vivo. 396 72