Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.22.32 (bromelain)
 1,025 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A mechanism of writhing reaction induced by kaolin, a known activator of factor XII, was studied. Kaolin induced a distinct writhing response, when injected intraperitoneally into mice (2.5 mg/mouse). The response disappeared in 15 min, but it was reproduced by intraperitoneal injection of captopril, 20 micrograms, into mice who had received the injection of kaolin 60 min before. This later response as well as the early one was not produced when mice were pretreated with bromelain (10 mg/kg, intravenously), 30 min before the kaolin administration. Therefore we determined if bromelain, a known depleter of plasma prekallikrein and a high molecular weight (HMW) kininogen, depletes those in mice. Plasma was collected from mice with or without pretreatment of bromelain, and kinin release of these plasma samples was examined by action of kaolin. The bromelain-treated mouse plasma released kinin amount of less than detection limit when activated with kaolin, whereas normal plasma released about 300 ng/ml of kinin of bradykinin equivalent as assessed by rat uterus contraction. Furthermore, activation of prekallikrein by kaolin was observed in mouse plasma as amidase activity to produce fluorescence from the synthetic substrate. It was completely diminished in the presence of soybean trypsin inhibitor. These results suggest that bromelain could deplete the HMW-kininogen in mouse plasma in the same way as in rat plasma. Furthermore, it is assumed that the kinin released from HMW-kininogen by kaolin could be responsible for inducing the writhing response.
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PMID:Kaolin-induced writhing response in mice: activation of the plasma kallikrein-kinin system by kaolin. 261 39

A mode of interaction of bradykinin with prostaglandins (PGs) in pain were compared with that in acute inflammation. When pain production was measured as an increase in reflex hypertensive response of the lightly anesthetized dogs after intrasplenic injection of bradykinin, the response was dependent to the doses (0.3-5 nmol) of bradykinin and that by the small doses (0.1-1 nmol) was blocked by intrasplenic infusion of indomethacin (0.54 mumol/min). The response to the threshold dose of bradykinin (0.3 nmol), which was suppressed during the indomethacin infusion, was potentiated by simultaneous injection of exogenous PGs. Order of the potency was PGI2 greater than PGH2 greater than PGE2 = TXA2 much greater than PGD2. Thus, it is clear that bradykinin induced pain through the generation of one of prostaglandins. On the other hand, the activity of bradykinin in plasma leakage was potentiated by simultaneous injection of PGE2, when tested in rabbit skin. In rat carrageenin-induced pleurisy, plasma prekallikrein was activated and high molecular weight (HMW) kininogen, not low molecular weight (LMW) kininogen, was consumed in the pleural cavity in the entire course of the pleurisy. Bradykinin played a role in plasma exudation in the pleurisy, because the plasma leakage was markedly inhibited in the rats, in which prekallikrein and HMW kininogen in plasma were depleted by intravenous bromelain. PGE2 was found in the pleural exudate, but the contribution of PGE2 itself to the plasma exudation seems to be only 10%. On the basis of the bradykinin release in the pleural cavity, once the PGE2 release was superimposed, the maximal plasma leakage was observed, indicating that PGE2 was released independently from bradykinin, and potentiated the plasma leakage by bradykinin.
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PMID:Different modes of interaction of bradykinin with prostaglandins in pain and acute inflammation. 381 4

Rat pleurisy was induced by intrapleural injection of lambda-carrageenin. The pleural exudate began to be accumulated 1-3 h after carrageenin administration and showed a peak at 19 h. The levels of prekallikrein and high-molecular-weight (HMW), but not low-molecular-weight (LMW), kininogen in the pleural fluid were markedly decreased when compared with those in plasma. Prekallikrein in rat plasma was activated by incubation with carrageenin in vitro. Captopril increased the plasma exudation significantly at 1-5 h. Depletion of prekallikrein and HMW kininogen in rat plasma by preadministration of bromelain caused marked inhibition of the plasma exudation at 1-24 h. The rest of the plasma exudation after bromelain was further decreased by simultaneous pretreatment of rats with both bromelain and aspirin. These results clearly indicate that plasma prekallikrein was activated in the pleural cavity and bradykinin released was responsible for plasma exudation during the entire course of this pleurisy.
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PMID:Activation of plasma kallikrein-kinin system and its significant role in pleural fluid accumulation of rat carrageenin-induced pleurisy. 634 79

Activation of bovine plasma prekallikrein was investigated with several proteinases. Highly purified bovine plasma prekallikrein was rapidly activated to kallikrein [EC 3.4.21.8] by bovine activated Hageman factor, trypsin [EC 3.4.21.4] and Pronase P (proteinases from Streptomyces griseus) and more gradually by papain [EC 3.4.22.2] and ficin [EC 3.4.22.3]. Activation of prekallikrein was also observed with bovine plasmin [EC 3.4.21.7], but not with bovine clotting factors Xa (Stuart factor) [EC 3.4.21.6] and IXa (Christmas factor) or thrombin [EC 3.4.21.5]. Urokinase [EC 3.4.99.26], Reptilase, collagenase [EC 3.4.24.3], elastase [EC 3.4.21.11], alpha-chymotrypsin [EC 3.4.21.1], Nagarse [EC 3.4.21.14], and stem bromelain [EC 3.4.22 4] did not convert prekallikrein to kallikrein. Plasma kallikrein activated to Hageman factor released kinin rapidly from bovine high molecular weight (HMW) kininogen. However, from bovine low molecular weight (LMW) kininogen, liberation of kinin was extremely slow. The kallikrein activity was inhibited by soybean trypsin inhibitor (SBTI), Trasylol, diisopropylfluorophosphate (DFP), and N-alpha-tosyl-L-lysine chloromethylketone (TLCK), but not by egg-white trypsin inhibitor (EWTI), lima bean trypsin inhibitor (LBTI), heparin or hexadimethrine bromide (Polybrene). The kallikrein formed an enzyme-inhibitor complex with SBTI and Trasylol, but not with LBTI. Prekallikrein did not react with SBTI. Prekallikrein consists of a single polypeptide chain of molecular weight about 90,000, as estimated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. Activation of prekallikrein by Hageman factor was found to involve cleavage of the single peptide bond on the disulfide-bridged polypeptide chain, and no change of molecular weight was observed during the activation. The peptide bond cleaved in prekallikrein by the activation was an Arg-X peptide bond on a disulfide-bridged polypeptide chain.
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PMID:Studies on prekallikrein of bovine plasma. II. Activation of prekallikrein with proteinases and properties of kallikrein activated by bovine Hageman factor. 676 24