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)

The cascade enterokinase-trypsinogen-prophospholipase A2 lecithin, generating trypsin, phospholipase A2 and lysolecithin, respectively, was studied in vitro using a novel phospholipase A2 assay. The rate of enterokinase catalysed activation of trypsinogen was maximal at 4 mmol/1 glycodeoxycholic acid; higher concentrations of bile salt progressively inhibited enterokinase activity. Net phospholipase A2 activity in reaction mixtures was critically dependent on the trypsin/prophospholipase A2 molar ratio. Lecithin hydrolysis by phospholipase A2 was dependent on the bile salt/lecithin molar ratio and was optimal at 1.25 to 1. The addition of enterokinase to lecithin and bile salt mixtures, containing trypsinogen and prophospholipase A2 at presumed pathophysiological concentrations, resulted in the generation of concentrations of lysolecithin lytic for pancreatic acinar cells within 5 min. These findings would support the concept that the entry of bile containing active enterokinase into the pancreatic duct system in vivo may in some cases be involved in the initiation of necrotising acute pancreatitis in man.
 ...
PMID:The generation of lysolecithin by enterokinase in trypsinogen prophospholipase A2 lecithin mixtures, and its relevance to the pathogenesis of acute necrotising pancreatitis. 390 74

Three hundred sixty Sprague-Dawley rats were allocated into four groups, according to different content of a 24-h i.v. infusion performed 1 h after intrabiliary injection of enterokinase/sodium taurocholate to induce acute pancreatitis (AP): (1) Saline; (2) 5 micrograms/kg/h nafamostat mesilate (FUT-175); (3) 10 micrograms/kg/h FUT-175; and (4) 25 micrograms/kg/h FUT-175. Peritoneal fluid was removed and exchanged with 1 mL 3.33 M fluorescein-isothiocyanate-conjugated (FITC) dextrans of 4000-40,000 Dalton. Serial blood samples were withdrawn and examined for FITC-dextrans, phospholipase A2 (PLA2), blood gases, amylase, and lipase. As compared to control (55%), FUT-175 brought about a lower (5 micrograms/kg/h: 25%) or no mortality (10 and 25 micrograms/kg/h), and a milder histological and biochemical evidence of AP. Untreated animals with PLA2 values over two times the standard deviation showed a respiratory distress. Further, unlike group 1, FUT-175 doses as low as 5 micrograms/kg prevented the increase in peritoneal permeability to small-size molecules (up to 20,000 Dalton). In a second experiment under the same drug protocol, 1000 U/mL of PLA2 and 2 mL of pancreatitis ascites were instilled ip. Peritoneal permeability to FITC-dextrans up to 30,000 Dalton and to PLA2 significantly increased in the saline group and in the 5 micrograms/kg FUT-175 group. However, 10 micrograms/kg and 25 micrograms/kg FUT-175 doses prevented such phenomenon. In conclusion, FUT-175 proves to be a potent antiprotease molecule with a biochemical activity also against PLA2 in vivo and prevents significant transperitoneal-blood access of pancreatic enzymes.
 ...
PMID:Nafamostat mesilate on the course of acute pancreatitis. Protective effect on peritoneal permeability and relation with supervening pulmonary distress. 752 62

Extracellular and secretory phospholipase A2 (PLA2), a class of phospholipid digesting enzyme, is widely distributed in animal venoms of reptiles and insects. Two cDNAs encoding PLA2 isoenzymes from Taiwan Cobra (Naja naja atra) were cloned into pQE-30 plasmid vector and expressed in Escherichia coli. The recombinant products were subjected to refolding using sulfonation under reduction/oxidation conditions with glutathione and enterokinase removal of His-tag, resulting in the active recombinant PLA2 with the same molecular masses of native enzymes as determined by mass spectrometry. The recombinant PLA2 was also shown by circular dichroism to possess a secondary structure similar to native PLA2. The enzymatic activity of the major isoenzyme (PLA2-1) is higher than the other minor isoenzyme (PLA2-2), which shows two amino acid difference from PLA2-1. Site-directed mutagenesis was used to probe the structure/function relationship of two highly conserved residues among all reported PLA2, i.e., His-47 and Asp-93. Replacement of His-47 residue by either Ala or Arg resulted in the complete loss of activity. Similarly, the mutant Asp-93 --> Asn (D93N) also retained little activity. These results suggest that both His-47 and Asp-93 are essential for the catalytic activity of PLA2. Computer graphic study, based on homology modelling, highlights the differences between native PLA2 isoenzymes and their site-directed mutants, which may account for the differences in the observed biological activity.
 ...
PMID:Characterization of phospholipase A2 (PLA2) from Taiwan Cobra: isoenzymes and their site-directed mutants. 973 49

Enteropeptidase inhibitor (DI) was isolated from bovine duodenum during purification of this enzyme. DI was purified by affinity chromatography on immobilised trypsin. DI preparations contain two main components: DI-9 (9 kD) and DI-20 (20 kD). The N-terminal amino acid sequence 1-19 of DI-9 is highly homologous to the Kunitz inhibitor (BPI). Molecular weights of DI-9 and BPI are the same (gel electrophoresis data). Fragment 1-19 of DI-9 differs from the corresponding region of BPI only at the position 17: DI-9 contains Ala-17 instead of Arg in BPI. The homology of N-terminal amino acid sequence 1-25 of DI-20 with the corresponding regions of some phospholipases A2 suggests that this protein is a new intestinal phospholipase A2. Inhibitor DI-9 and phospholipase DI-20 are probably isolated in a common lipoprotein complex. The only earlier known in vitro inhibitor of enteropeptidase, BPI, was localised in vivo in different tissues with this enzyme. In our opinion the Kunitz-type inhibitor DI-9 is, a physiological inhibitor of enteropeptidase.
 ...
PMID:[An inhibitor of enteropeptidases and trypsin from the bovine duodenum]. 984 20

Addition of alpha-thrombin to quiescent IIC9 cells results in the activation of lipid-metabolizing enzymes associated with signal-transduction cascades. These enzymes include phosphatidylinositol (PI)-specific phospholipase C (PI-PLC), phosphatidylcholine (PC)-specific phospholipases C and D and phospholipase A2 (PLA2). Whereas the alpha-thrombin receptor has been shown to couple with PI-PLCs, it is not clear whether this receptor, or a putative second receptor, couples to one or more of the other phospholipases. In this report we determine whether the cloned receptor couples to all or a subset of these enzymes. We show that (i) an alpha-thrombin-receptor-activating peptide also elicits the above responses and (ii) addition of enterokinase to IIC9 cells, stably transfected with an alpha-thrombin receptor (enterokinase- responsive alpha-thrombin receptor, EKTR) containing an enterokinase cleavage site in place of an alpha-thrombin cleavage site, stimulates both PI and PC hydrolysis, including PLA2. Enterokinase also induces mitogenesis in the IIC9s transfected with EKTR. These results indicate that, in addition to initiating a mitogenic signalling cascade, the cloned alpha-thrombin receptor couples to enzymes involved in generating PC-derived, as well as PI-derived, second-messenger molecules in IIC9s. Additionally, using the cells transfected with EKTR, we further demonstrate that only activated, i. e. cleaved, receptors are desensitized.
 ...
PMID:Dual coupling of the alpha-thrombin receptor to signal-transduction pathways involving phosphatidylinositol and phosphatidylcholine metabolism. 985 30

The activation of endogenous pancreatic enzymes during automated pancreas digestion may be detrimental to islet isolation. In this report we assessed the activation of trypsin, chymotrypsin, elastase, carboxypeptidases A and B, phospholipase A2, and lipase using a porcine model. Four islet isolations were examined. Duplicate aliquots were taken from the automated circuit at 5-min time intervals up to the completion of pancreas digestion (approx 60 min). One aliquot was activated in vitro with exogenous trypsin in order to convert the enzymes into their active non-"proform," with the exception of trypsinogen, which was activated with exogenous enterokinase. This was done to assess the percentage activation of each individual enzyme (total potentially activatable enzyme release). The extent of activation between isolations was extremely variable. During the closed (recirculating) circuit phase of pancreas digestion there were both gradual and rapid increases in the levels of enzymes released. Peak activity of enzyme activation varied from 13 to 30 min; similarly, total potentially activatable peaks occurred between 13 and 38 min. Lipase and carboxypeptidase B showed greater than 70% activation, chymotrypsin, carboxypeptidase A, and phospholipase A2 between 50% and 70% activation, and trypsin and elastase less than 20%. There were up to 30-fold differences between the four islet preparations. In summary, it is unlikely that poor islet yields are soley explained by variations between collagenases; the variable activation of endogenous pancreatic exocrine enzymes is also likely to be influential to porcine islet yields.
 ...
PMID:A preliminary study of the activation of endogenous pancreatic exocrine enzymes during automated porcine islet isolation. 1044 39