Generation of Active Trypsin by Chemical Cleavage
14
Citation
28
Reference
10
Related Paper
Citation Trend
Keywords:
Enteropeptidase
Cleavage (geology)
A simple and selective assay method for a trypsin-sensitive cholecystokinin (CCK)-releasing peptide ('monitor peptide') found in rat bile-pancreatic juice is reported. This peptide also has trypsin inhibitory activity which could be used as an index for measurement, except that it was difficult to assay the inhibitory activity of the peptide directly in the bile-pancreatic juice because of abundant endogenous trypsin. The peptide and trypsin were purified from rat bile-pancreatic juice, and their sensitivities to heat treatment was examined. Trypsin(ogen) was completely eliminated by being heated at 80°C for 40min in the presence of 0.5 M NaCl, pH 2.5, whereas the trypsin inhibitory activity of the peptide was above 95% of the original level after this treatment. Using the difference, we established assay conditions for trypsin inhibition by the peptide in which the effects of endogenous trypsin were removed by heating. This assay method was then used to show that there was a close relationship between trypsin(ogen) and the peptide in the bile-pancreatic juice. We estimated that the trypsin inhibitory activity of the peptide masks 2-5% of the trypsin activity in the bile-pancreatic juice from Wistar male rats fed a stock diet. The optimum conditions for activation of trypsinogen and chymotrypsinogen in rat bile-pancreatic juice were also studied. At 37°C, trypsinogen and chymotrypsinogen were maximally activated by enterokinase 5% of protein being activated for 40 and 6 min, respectively.
Pancreatic juice
Enteropeptidase
Chymotrypsinogen
Cite
Citations (3)
Enteropeptidase
Cite
Citations (6)
The effect of heparin on the activation of trypsinogen by enterokinase and on trypsin activity has been investigated. Proteolytic activity of trypsin has been determined using caseinolytic method. It has been found that heparin inhibits trypsinogen activation only when it is preincubated with proenzyme before introduction of enterokinase to the tested system. In these experimental conditions heparin in final concentrations from 1 to 20 U/ml exhibits inhibitory effect diminishing trypsinogen activation to about 65% initial activity and in higher concentrations only to 50%. Heparin introduced to the tested system simultaneously with enterokinase or to the active trypsin did not appear evident inhibitory effect.
Enteropeptidase
Cite
Citations (10)
The role of enteropeptidase and trypsin in the process by which pancreatic proteolytic zymogens are converted into active enzymes has been investigated in the past, using purified enzymes and proenzymes of animal origin. In the present study, we wanted to study this process under conditions which come near to the physiological situation, which prevails in the human duodenum and upper small intestine.Duodenal contents were collected from 2 patients with intestinal enteropeptidase deficiency. The samples expressed no tryptic activity and were used as the source of zymogens. Enteropeptidase or trypsin was added to these samples and the process of zymogen activation was followed by measuring trypsin and chymotrypsin activities.When exogenous trypsin was added to the duodenal contents of patients with enteropeptidase deficiency, having no tryptic activity, activation of intrinsic trypsinogen was not observed. When purified porcine or human enteropeptidase was added to the same samples of duodenal contents, this resulted in a rapid, dose-dependent activation of trypsinogen followed by the activation of chymotrypsinogen.The study underlines the key role of enteropeptidase in the cascade process, which leads to the presence of active proteolytic enzymes in the human small intestine. The results also explain why patients with congenital deficiency of enteropeptidase are unable to activate trypsinogen by alternative pathways and therefore suffer from a severe disturbance of protein digestion with failure to thrive at young age, hypoproteinemia, and anemia.
Enteropeptidase
Zymogen
Chymotrypsinogen
Cite
Citations (2)
The molecular forms of immunoreactive pancreatic cationic trypsin in sera of patients with acute pancreatic inflammation have been characterized using a radioimmunoassay technique that is capable of detecting trypsinogen as well as trypsin bound to alpha 1-antitrypsin. Trypsin bound to alpha 2-macroglobulin is not immunoreactive under normal assay conditions. However, alpha 2-macroglobulin-bound trypsin can be detected after gel filtration of serum on Bio-Gel A-0.5 m and acid treatment of column fractions. The average serum level of immunoreactive cationic trypsin from 20 patients with acute pancreatic inflammation was 1,590 ng/ml. An average normal value of 26 ng/ml has been obtained previously. Serum samples from 14 patients with pancreatic inflammation were chromatographed under conditions that resolve trypsinogen, alpha 1-antitrypsin-bound trypsin, and alpha 2-macroglobulin-bound trypsin. In each case, the major portion of the immunoreactive material eluted at a position corresponding to free trypsinogen, while a minor fraction of the immunoreactive material appeared to be trypsin bound to alpha 1-antitrypsin. The zymogen nature of the major peak was confirmed in one case by activation with human enteropeptidase. In 11 of 14 patients, acid treatment of the alpha 2-macroglobulin peak yielded immunoreactive trypsin.
Zymogen
alpha-2-Macroglobulin
Enteropeptidase
Cite
Citations (58)
Enteropeptidase
Cite
Citations (9)
Enteropeptidase
Cite
Citations (2)
Enteropeptidase
Zymogen
Benzamidine
Cite
Citations (53)
Enteropeptidase
Cite
Citations (50)
For the activation of trypsinogen by enterokinase the optimal concentration of calcium chloride was near 0.0002 M, which is at the lower end of the range of calcium concentrations prevailing in the upper small intestine. Magnesium chloride was not so effective. For an hour's activation at pH 7.7 and 23°, in the presence of 0.0002 M calcium chloride, the rate of trypsin production was directly proportional to the concentration of enterokinase. This system was used for a simplified assay of trypsinogen-activator; and calcium was varied according to whether the activator was enterokinase or trypsin. Although partially purified enterokinase had much more trypsinogen-activating effect than an equal weight of crystallized trypsin, it had much less hydrolytic effect on lysine methylester and tosylarginine methylester. In comparison with trypsin, enterokinase is more precisely adapted to the activation of trypsinogen.
Enteropeptidase
Cite
Citations (3)