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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although several factors are involved in the invasive behavior of E. histolytica, proteinases seem to play a key role. Different proteinases have been found in virulent trophozoites of this parasite. Cytosols of clones A, 32-1 462-1 and L-6 of E. histolytica exhibiting various degrees of virulence were used to study the activity of trypsin-like, plasminogen activator and cathepsin B neutral proteinases with specific synthetic oligopeptides. Cathepsin-B like activity showed the highest values in highly virulent clone A, which is derived from virulent strain HM1:IMSS. On the contrary, non virulent clones had very low activity. Clone L-6, a non virulent subclone of strain HM1:IMSS, retained some cathepsin B-like activity. Trypsin-like and plasminogen activator assays revealed low activity and no differences between virulent and non-virulent clones were found. It is concluded that the Arg-Arg-thiol proteinase (Cathepsin B-like) is a good virulence marker.
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PMID:Neutral proteinase activities in different strains and clones of Entamoeba histolytica. Correlation with virulence. 134 Mar 1

The Kunitz-type trypsin and tissue plasminogen activator (t-PA)-inhibitor from Erythrina caffra seeds was cleaved by trypsin at low pH to yield a disulphide linked two-chain molecule with reduced hydrophobicity. This change was used to separate cleaved from native inhibitor by phenyl-Sepharose chromatography. The inhibitor was not cleaved by t-PA. Trypsin, but not t-PA, catalysed resynthesis of the cleaved bond. Although the cleaved protein retained inhibitory activity for both trypsin and t-PA, 6-10 times higher concentrations were required for equivalent inhibition. Removal of the active site arginine (Arg63) from the cleaved inhibitor by digestion with carboxypeptidase B resulted in a further loss of inhibitory activity towards both proteases. The activity of the inhibitor could also be decreased by modification of one susceptible arginine residue with peptidyl arginine deiminase. These results suggest that the trypsin-reactive site of the Erythrina inhibitor is also involved in the interaction between the inhibitor and t-PA.
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PMID:The Erythrina protease inhibitor: interactions with tissue plasminogen activator. 177 16

The role of the plasmin-generating system, a serum component, in the development of dissociated embryonic chick spinal cord cells in culture was studied. Studies were performed in a defined system where the cells were maintained in a serum-free medium. Under these conditions the cells produce plasminogen activator. It was found that plasminogen, when added to the chemically defined culture medium at concentrations of 0.2-0.75 microgram/ml, stimulates [3H]thymidine uptake (as expressed per total DNA) in a dose-response manner. This mitogenic effect is abolished by the protease inhibitors leupeptin and aprotinin. Trypsin, but not chymotrypsin, can produce similar effects. It is concluded that plasmin, which is produced as a result of the activation of plasminogen, is a component that serves as a proliferation factor in developing spinal cords in culture.
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PMID:Role of the plasmin-generating system in the developing nervous tissue: I. Proteolysis as a mitogenic signal for the glial cells. 621 10

State of the anticoagulation system was studied after intravenous administration of trypsin at doses similar to the concentration of alpha-thrombin, activating chemoreceptors of vascular walls. Trypsin at doses 0.5 microM-3.7 microM did not affect the anticoagulation system as indicated by unaltered rate of nonenzymatic fibrinolysis. Occurrence of trypsin in blood led to generation of thrombin, which caused limited proteolysis of fibrinogen with subsequent increase in content of soluble fibrin, but did not stimulate the anticoagulation system. Distinct stimulation of the enzymatic fibrinolysis resulted from both liberation of plasmin due to direct proteolysis of plasminogen and unspecific release of the plasminogen activator after destruction of vascular endothelium. High doses of alpha-thrombin (70 NIH un per 1 ml of the preparation) did not activate the anticoagulation system but the total fibrinolytic activity was increased die to elevation in the ratio of enzymatic fibrinolytic activity. The data obtained suggest that the proteolytic activity of thrombin and trypsin is not responsible for the reflectory reaction of the anticoagulation system. High specificity of alpha-thrombin, caused by the presence in its structure of the recognizing sites of high molecular substrates, enables the enzyme to interact with chemoreceptors of vascular walls and to stimulate the anticoagulation system.
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PMID:[Enzymic and non-enzymic fibrinolysis during intravenous administration of trypsin]. 654 8

The reflex response of anticoagulating system was studied in perfusion of humorally isolated sinocarotid area with trypsin and alpha-thrombin in rabbits with intact neural connections. Trypsin (1.5 and 3.8 microM) does not induce a reflex release of heparin and plasminogen activator into the blood flow whereas alpha-thrombin (0.5 microM) activates the anticoagulating system which is evident from elongation of the recalcification period, augmentation of total fibrinolytic activity and non-enzyme fibrinolysis of the blood plasma. The level of plasminogen activator sharply rises in the blood with no significant augmentation of the plasmin activity. The data obtained suggest that the specific nature of thrombin in due to the area of high-molecular substrates binding rather than proteolytic activity. Chemoreceptors of the sinocarotid area fail to respond to thrombin after trypsin perfusion which suggests failure of the receptor apparatus after contact with trypsin.
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PMID:[Comparative analysis of the effect of alpha-thrombin and trypsin on the state of the anticoagulating system]. 668 61

Barley serpin BSZx is a potent inhibitor of trypsin and chymotrypsin at overlapping reactive sites (Dahl, S.W., Rasmussen, S.K. and Hejgaard, J. (1996) J. Biol. Chem., in press). We have now investigated the interactions of BSZx with a range of serine proteinases from human plasma, pancreas and leukocytes, a fungal trypsin and three subtilisins. Thrombin, plasma kallikrein, factor VIIa/tissue factor and factor Xa were inhibited by BSZx at heparin independent association rates (k(ass)) of 4.5 X 10(3)-1.3 x 10(5) M(-1) s(-1) at 22 degrees C. Only factor Xa turned a significant fraction of BSZx over as substrate. Complexes of these proteinase with BSZx resisted boiling in SDS, and amino acid sequencing showed that cleavage in the reactive center loop only occurred after P1 Arg. Activated protein C and leukocyte elastase were slowly inhibited by BSZx (k(ass)=1-2 x 10(2) M(-1) s(-1)) whereas factor XIIa, urokinase and tissue type plasminogen activator, plasmin and pancreas kallikrein and elastase were not or only weakly affected. The inhibition pattern with mammalian proteinases reveal a specificity of BSZx similar to that of antithrombin III. Trypsin from Fusarium was not inhibited while interaction with subtilisin Carlsberg and Novo was rapid but most BSZx was cleaved as a substrate. Identification of a monoclonal antibody specific for native BSZx indicate that complex formation and loop cleavage result in similar conformational changes.
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PMID:Inhibition of coagulation factors by recombinant barley serpin BSZx. 884 56

The role played by serine proteinases with trypsin-like specificity in chondrocyte-mediated cartilage proteoglycan breakdown was investigated by use of a selective proteinase inactivator, 7-amino-4-chloro-3-(-3-isothiureidopropoxy)isocoumarin, in explant culture systems. This compound was a rapid inactivator of urokinase-type plasminogen activator. It potently inhibited interleukin 1- and tumor necrosis factor-stimulated proteoglycan release from both nasal and articular cartilage. Its less potent inhibition of basal and retinoic acid-stimulated release appeared to be due to cytotoxic effects. The functional half-life of the inactivator in culture medium was 95 min, and its concentration in cartilage was 2.5-fold higher than in the surrounding medium. Following spontaneous hydrolysis the breakdown products of the inactivator were unable to inhibit proteoglycan release. Trypsin-like activity was demonstrated by enzyme histochemistry to be chondrocyte-associated and inhibited by the serine proteinase inactivator. Cell-associated and secreted plasminogen activator activity was detected by zymography. These results suggest the involvement of a serine proteinase(s) with trypsin-like specificity, possibly urokinase-type plasminogen activator, in chondrocyte-mediated cartilage proteoglycan breakdown occurring as a result of stimulation with proinflammatory cytokines. Basal proteoglycan breakdown may occur via a different pathway. Our findings point to a pathological role for serine proteinase(s) in the development of cartilage diseases such as arthritis, possibly in a cascade which results in the activation of the enzyme(s) directly responsible for proteoglycan breakdown. It remains to be shown whether the target serine proteinase is urokinase-type plasminogen activator.
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PMID:A serine proteinase inactivator inhibits chondrocyte-mediated cartilage proteoglycan breakdown occurring in response to proinflammatory cytokines. 964 62

Synthetic melittin mediated the release of [3H]-oleic acid ([3H]-OA) or its acylated lipids from [3H]-OA-labeled E. coli cells exposed to human serum. This phenomenon was not observed in the absence of serum and was calcium independent. The addition of serum was not required for melittin-mediated lysis of erythrocytes, although lysis was greater in the presence of serum than in its absence (P<0.001). Trypsin treatment of human serum reduced the melittin-mediated release of [3H]-OA/acylated lipids, and this effect was more pronounced upon boiling the serum (P<0.01). A kinetic study showed that maximum release of [3H]-OA/acylated lipids occurred within 3-6 min. Thin layer chromatography (TLC) analysis showed the lipids to be phosphatidyl ethanolamine (PE), phosphatidylethanol (PEt) and phosphatidic acid (PA). There was no detectable level of oleic acid (OA), diacylglycerol (DAG), phosphatidyl choline (PC) or phosphatidyl serine (PS). These findings suggested that a trypsin and heat-sensitive enzyme/factor present in the serum had a role in melittin-mediated action. These findings further showed that melittin activated phospholipase D (PLD), without affecting phospholipase A(2) (PLA(2)) or phospholipase C (PLC) activity.
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PMID:Melittin-mediated release of [3H]-oleic acid from E. coli cells is dependent upon heat- and trypsin-sensitive factor(s) in human serum. 1070 99

We characterized the tracheal and bronchial relaxation caused by proteinase-activated receptor-2 (PAR-2) activation in ddY mice and/or in wild-type and PAR-2-knockout mice of C57BL/6 background. Ser-Leu-Ile-Gly-Arg-Leu-amide (SLIGRL-NH(2)) and Thr-Phe-Leu-Leu-Arg-amide, PAR-2- and PAR-1-activating peptides, respectively, caused relaxation in the isolated ddY mouse trachea and main bronchus. The relaxation was abolished by specific inhibitors of cyclooxygenase (COX)-1, COX-2, mitogen-activated protein kinase kinase (MEK), and p38 MAP kinase. The MEK and p38 MAP kinase inhibitors did not affect prostaglandin E(2)-induced relaxation. Inhibitors of cytosolic Ca(2+)-dependent phospholipase A(2) (PLA), Ca(2+)-independent PLA(2), diacylglycerol lipase, tyrosine kinase, and protein kinase C exhibited no or only minor inhibitory effects on the PAR-mediated relaxation. Trypsin, a PAR-2 activator, and 2-furoyl-Leu-Ile-Gly-Arg-Leu-amide, a potent PAR-2-activating peptide, in addition to SLIGRL-NH(2), caused airway relaxation in wild-type C57BL/6 mice, as in ddY mice. In PAR-2-knockout mice, the peptide effects were absent and the potency of trypsin decreased. Desensitization of PAR-2 and/or PAR-1 greatly suppressed the relaxant effect of trypsin. The bronchial and tracheal tissues displayed distinct sensitivities toward trypsin and the PAR-2-activating peptides. Our data indicate an involvement of both COX-1 and COX-2, and the MEK-extracellular signal-regulated kinase and p38 MAP kinase signaling pathways in the PAR-2- and PAR-1-triggered relaxation of mouse airway tissue, and substantiate a role for PAR-2 in regulating both the trachea and bronchial responsiveness in the mouse lung.
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PMID:Proteinase-activated receptor-2-mediated relaxation in mouse tracheal and bronchial smooth muscle: signal transduction mechanisms and distinct agonist sensitivity. 1519 93

The substrate specificity of alpha-chymotrypsin and other serine proteases, trypsin, elastase, proteinase K and subtilisin, towards hydrolysis of various polyesters was examined using poly(L-lactide) (PLA), poly(beta-hydroxybutyrate) (PHB), poly(ethylene succinate) (PES), poly(ethylene adipate) (PEA), poly(butylene succinate) (PBS), poly(butylene succinate-co-adipate) (PBS/A), poly[oligo(tetramethylene succinate)-co-(tetramethylane carbonate)] (PBS/C), and poly(epsilon-caprolactone) (PCL). alpha-Chymotrypsin could degrade PLA and PEA with a lower activity on PBS/A. Proteinase K and subtilisin degraded almost all substrates other than PHB. Trypsin and elastase had similar substrate specificities to alpha-chymotrypsin.
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PMID:Hydrolysis of polyesters by serine proteases. 1592 50


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