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)

The catalytic properties of the two human trypsins obtained from purified trypsinogens have been studied. The catalytic rate constant kcat and the pK of the ionisable residue implicated in the active site have been determined with Bz-Arg-OEt. The hydrolysis of Tos-Arg-OMe by human trypsins does not follow the simple Michaelis-Menten scheme and indicates a difference in the conformational flexibility of the active site-regions of the two enzymes. Both enzyme are readily autolyzed and calcium ion plays a fundamental role in stabilizing trypsin activity. However trypsin 2 self-digests more rapidly than trypsin 1. These results are a prerequisite to the elucidation of the fate of pancreatic enzymes in human digestive tract.
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PMID:The two human trypsinogens: catalytic properties of the corresponding trypsins. 2 65

The activation of human trypsinogens 1 and 2 by porcine enterokinase at pH 5.6 shows that the two human zymogens are equivalent substrates for this enzyme and that both proteins are activated faster than the cationic bovine trypsinogen. At pH 8.0 and in the presence of 20 mM calcium the two human trypsinogens are activated by either human trypsin at the same rate but the affinity of both trypsins is higher for trypsinogen 1 than for trypsinogen 2. Two Ca2+ binding sites are identified in the two human zymogens and their pK(Ca2+) values determined. For trypsinogen 1 the values are respectively of 2.8 and 3.3 for the primary and secondary Ca2+ binding sites, and for trypsinogen 2 of 3.4 and 2.7. These values are markedly different from those obtained for bovine cationic trypsinogen, especially in the case of trypsinogen 1. These results point out a different degree of saturation of the calcium binding sites of the 2 human zymogens that must exist in physiological conditions, suggesting different biological activities of the two trypsinogens.
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PMID:Comparative studies on the mechanism of activation of the two human trypsinogens. 50 71

Human trypsins 1 and 2 both converted Met-Lys-bradykinin to bradykinin and released bradykinin from kininogen in human plasma as measured by bioassay with the isolated guinea pig ileum. Porcine kallikrein did not act on Met-Lys-bradykinin and released kallidin from human kininogen. Since human trypsin 1 is only partially and trypsin 2 completely inhibited by soybean trypsin inhibitor, these data show that the criterion of susceptibility to soybean trypsin inhibitor cannot be used to discriminate between trypsin and kallikrein of different species.
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PMID:Comparison of the kininogenase activity of human pancreatic trypsins and porcine Kallikrein on Met-Lys-bradykinin and human plasma kininogen. 71 Nov 61

Two monoclonal antibodies (Mab) raised against human pancreatic trypsin 1, Mab G6 and A8, were previously isolated and characterized. The two Mab which recognize trypsinogen 1 are found to inhibit the activation of trypsinogen 1 by enterokinase. The inhibition of activation by the two Mab is concentration-dependent, rapid and virtually complete with Mab G6. Activation of trypsinogen 2 is totally inhibited by Mab G6, while Mab A8 has no effect on the activation of trypsinogen 2. The two monoclonal antibodies have opposite effects on the proteolytic activity of trypsin 1; Mab G6 increases proteolytic activity while Mab A8 inhibits trypsin activity by as much as 40%. This inhibition is concentration dependent but cannot account for the complete inhibition of activation of trypsinogen 1. Neither monoclonal antibody significantly inhibits the esterolytic activity of either form of human trypsin. Western-blot analysis of the reactivity of the two monoclonal antibodies with trypsinogens of various species shows that only Mab G6 cross-reacts with dog trypsinogen.
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PMID:Monoclonal antibodies to human pancreatic trypsin 1 inhibit the activation of human trypsinogens 1 and 2. 137 Dec 52

Graft pancreatitis and allograft rejection were both accompanied by increased serum levels of immunoreactive anionic trypsin (irAT) in a porcine pancreatic allograft transplantation model. Characterization of this immunoreactivity by gel filtration revealed different elution profiles in these conditions that can be helpful in the differentiation between them. During graft pancreatitis, a major part of the immunoreactivity was found within the high-molecular-weight fraction corresponding to the formation of complexes between trypsin and protease inhibitors. During allograft rejection, virtually all serum irAT increase could be attributed to the release of anionic trypsinogen without any evidence of activation. Since this transplantation model includes urinary diversion of the exocrine secretions, irAT and immunoreactive cationic trypsin (irCT) can also be measured in the urine. Characterization of this immunoreactivity showed that most of both irAT and irCT was found as active trypsin but a minor part was probably complexed with some protease inhibitor (possibly pancreatic secretory trypsin inhibitor [PSTI]).
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PMID:Characterization of immunoreactive trypsin as a means of differentiating graft pancreatitis and allograft rejection after porcine pancreatic transplantation. 173 80

Proteins with trypsin-like immunoreactivity (first detected by a specific immunoenzymatic assay) were isolated from CAPAN-1 and CFPAC-1 cell culture-conditioned media by chromatography on an immunoadsorbent prepared with a polyclonal antibody directed against trypsin 1. The adsorbed proteins were devoid of free trypsin activity but trypsin activity was present after enterokinase activation demonstrating that the immunoreactive trypsin present in cell supernatants corresponds to trypsinogens. When characterised by Western blotting using a monoclonal antibody directed against human trypsin 1 two protein bands corresponding to trypsinogen 1 (23 kDa) and trypsinogen 2 (25 kDa) gave a positive reaction. These results demonstrate the presence of trypsinogens 1 and 2 in CAPAN-1 and CFPAC-1 cells and in their culture-conditioned media.
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PMID:Characterization of trypsinogens 1 and 2 in two human pancreatic adenocarcinoma cell lines; CFPAC-1 and CAPAN-1. 175 57

Urine cytology and blood lymphocyte blastogenesis were evaluated as indicators of allograft rejection in a porcine pancreatic transplantation model. The percentage of activated lymphocytes and/or blasts was significantly increased during the rejection phase. Positive cytology was present in all rejection episodes. An increased thymidine uptake of blood lymphocytes and a decreased uridine/thymidine uptake quotient were seen prior to the onset of rejection. The reported dissociation of anionic and cationic trypsin levels in serum and urine after transplantation was not seen after simple urinary diversion of the pancreatic juice. This supports the hypothesis that a decreased synthesis of cationic trypsinogen compared with anionic trypsinogen occurs after porcine pancreatic transplantation.
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PMID:Early indicators of allograft rejection in a porcine pancreatic transplantation model. 187 58

We have recently demonstrated that many cancer cell lines produce a novel trypsinogen isoenzyme called tumor-associated trypsinogen 2 (TAT-2). It was found during a search of the target protease for tumor-associated trypsin inhibitor (TATI). We now show that degradation of subendothelial cell extracellular matrix (ECM) by four different cell lines (COLO 205 colon carcinoma, K-562 erythroleukemia, CAPAN-1 pancreatic carcinoma, and HT 1080 fibrosarcoma) can be partially inhibited by TATI or neutralizing trypsin antibodies. When cells were cultured in serum-free medium on ECM, TATI and trypsin antibodies inhibited the release of immunoreactive fibronectin fragments from ECM by 47-54 and 40%, respectively. Degradation of isotopically labeled ([3H]serine, [3H]proline, and [35S]sulfate) ECM was also significantly prevented by TATI. At its maximum, it exerted a 57% inhibition on the degradation of [3H]serine-labeled ECM. Plasminogen added exogenously to the culture medium further potentiated the proteolysis of ECM. Interestingly, addition of enteropeptidase, an activator of TAT-2, also enhanced cell-mediated proteolysis as assessed by degradation of purified fibronectin coated onto the surface of wells. Immunoblot analysis showed that enteropeptidase-mediated proteolysis generated a pattern of fibronectin fragments similar to that obtained by digestion of purified fibronectin by TAT-2. These results demonstrate the existence of a proteolytic system in tumor cells which is dependent on the activation of TAT-2. We suggest that TAT-2 is involved in a protease cascade-stimulating tumor cell invasion and degradation of extracellular matrix.
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PMID:Tumor-associated trypsin participates in cancer cell-mediated degradation of extracellular matrix. 200 30

We have developed sensitive time-resolved immunofluorometric assays for the two trypsinogen isoenzymes, trypsinogen-1 and trypsinogen-2, which also are called cationic and anionic trypsinogen, respectively. The assays use monoclonal antibodies produced by immunization with tumor-associated trypsinogen that is isolated from mucinous ovarian cyst fluid. In each assay, one antibody is immobilized onto the walls of polystyrene microtiter strip wells and the other is labeled with an europium(III) chelate. The cross-reaction of each trypsinogen isoenzyme in the assay for the other isoenzyme is less than 1%. The detection limits are 0.1 micrograms/L for trypsinogen-1 and 0.3 micrograms/L for trypsinogen-2. In sera of healthy subjects and patients with extrapancreatic disease the concentration of trypsinogen-1 is higher (median, 21 micrograms/L) than that of trypsinogen-2 (median, 17 micrograms/L), but in acute pancreatitis the ratio is reversed. In acute pancreatitis the concentration of trypsinogen-2 is 50-fold higher than in controls, whereas the difference in trypsinogen-1 concentrations is only 15-fold. The corresponding difference in immunoreactive trypsin measured by a commercially available radioimmunoassay was also only 10-fold.
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PMID:Time-resolved immunofluorometric assays for trypsinogen-1 and 2 in serum reveal preferential elevation of trypsinogen-2 in pancreatitis. 236 31

1. Ninety male Wistar rats were divided into two groups. A control group (C) was fed on a balanced diet, containing 200 g protein/kg for 51 d. An experimental group (E) was fed on a low-protein diet containing 50 g protein/kg for 28 d (PM), and then on a balanced diet for 23 d (BR). At different days of PM and BR, the pancreas and the pancreatic juice were collected 40 min after injection of 0.1 mCi [3H]leucine. The amounts of amylase (EC 3.2.1.1), trypsinogen 2 (EC 3.4.21.4), chymotrypsinogen 1 (EC 3.4.21.1) and lipase (EC 3.1.1.3) were determined after separation by the isoelectric focussing technique. Incorporation of [3H]leucine into the four hydrolases of pancreatic juice and pancreas was also determined. 2. In control rats a progressive increase in the concentration of digestive enzymes and the amounts secreted were observed with age. Maturation was reached when the rats were 9 weeks old. In rats E, PM inhibited maturation of the pancreas. However, individual enzymes were not affected to the same extent and at the same time. As soon as re-feeding was initiated, pancreas maturation took place and a significant increase in these variables was observed. The increases varied according to the hydrolase and did not appear at the same time. 3. In control rats, a preferential secretion of newly synthesized enzymes was observed in young rats, whereas with age, the proportion of newly synthesized enzymes excreted decreased slowly. In group E rats, at the beginning of PM, the proportion of newly synthesized enzymes secreted was very low and increased with time. 4. In rats C and E, our results indicated a non-parallelism between pancreatic enzyme levels and amounts secreted. This non-parallelism was different in both groups, it was changed with age and pancreas maturation in group C, and according to nutritional state in group E.
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PMID:Effects of age, and protein malnutrition followed by a balanced diet on the non-parallel change in digestive enzymes in the pancreas and their secretion in the rat. 246 65


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