Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Studies were conducted on the mechanism of the stimulatory effect of 6-aminohexanoic acid (6-AH) during the in vitro activation of human glutamic plasminogen (Glu-Plg) by streptokinase or by tissue plasminogen activator (t-PA) and the possible role of the addition of physiological concentrations of NaCl to the buffer solution. Enhancement by 6-AH was investigated by measuring the rate of plasmin generation using chromogenic substrate H-D-glu-phe-lys-pNA (S-2403). Control studies using plasmin showed that the addition of 6-AH at concentrations below 20 mM did not significantly affect the initial rate of the amidolytic activity of plasmin with or without the addition of NaCl to 0.05 M Tris buffer (pH 7.4). On the other hand, addition of NaCl to the buffer slowed down the initial rate of activation of Glu-Plg by streptokinase or by t-PA while increasing the percent enhancement by 6-AH when compared with the controls. The ratios of the initial rates of plasmin generation in the presence or in the absence of 6-AH were plotted against the inverse of the volume fraction of Glu-Plg, streptokinase or t-PA after serial dilutions. The results showed that when the activation reactions were performed in 50 mM of Tris buffer (pH 7.4), the enhancements by 6-AH were related to its interaction with streptokinase or t-PA, while using the same Tris buffer containing 0.6 % NaCl, the enhancements by 6-AH were related to its interaction with both Glu-Plg and streptokinase or t-PA. However, upon increasing the NaCl to 0.9%, the results showed that the enhancements by 6-AH of the activation of Glu-Plg by streptokinase or t-PA were related to its interaction with Glu-Plg. The results suggested that changes in the concentrations of NaCl play a regulatory role during the activation process.
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PMID:Mechanism of the stimulatory effect of 6-aminohexanoic acid on plasminogen activation by streptokinase or tissue plasminogen activator: the role of chloride. 1474 74

Native Fucoidan and unfractionated heparin enhanced by 6-fold the in vitro activation of human glutamic plasminogen (Glu-Plg) by tissue plasminogen activator (t-PA) using 0.05M Tris buffer pH 7.4, while sulfated fucoidan inhibited the activation under these conditions. Double reciprocal plots of these interactions showed that sulfated fucoidan inhibited the activation in a noncompetitive manner while the enhancements by heparin or native fucoidan were due to an increase of Vmax without affecting Km. To determine whether the stimulatory effect of the individual cofactor was due to its interaction with Glu-Plg or with t-PA, experiments were performed at a fixed level of the cofactor and either varying in a serial fashion the concentration of Glu-Plg or of t-PA. The ratios of the initial rate of plasmin generation in the presence or absence of the cofactors were plotted against the inverse of the volume fraction of Glu-Plg or of t-PA. The results showed that heparin interacted with Glu-Plg while native fucoidan and sulfated fucoidan interacted with t-PA. Studies were also conducted on the effect of the two fucoidans and heparin on the activation of Glu-Plg by t-PA using 0.05M Tris buffer pH 7.4 containing 0.1 M NaCl. Under these conditions, sulfated fucoidan was most effective in enhancing the activation followed by native fucoidan and heparin respectively. The results of this study showed that in presence of the buffer containing 0.1 M NaCl, heparin was interacting with t-PA while the two fucoidans were interacting with both t-PA and Glu-Plg. A comparison of the double reciprocal plots of the rate of enhancement by the cofactors using 0.05M Tris buffer pH 7.4 containing 0.1M NaCl or in presence of buffer alone showed that the cofactors were more effective using 0.05M Tris buffer pH 7.4 alone and that addition of NaCl to the buffer slowed down the reactions by decreasing Vmax without affecting Km. Circular Dichroism (CD) studies of Glu-Plg in the far ultraviolet (UV) range showed that addition of NaCl destabilized the beta sheet structure which was reversed by addition of 6-aminohexanoic acid (6-AH) or one of the cofactors, while the near UV CD spectra of Glu-Plg in presence of 0.1 M NaCl was enhanced by the cofactors by increasing its ellipticity as reported earlier for 6-AH.
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PMID:Mechanism of the stimulatory effect of native fucoidan, highly sulfated fucoidan and heparin on plasminogen activation by tissue plasminogen activator: the role of chloride. 1572 89

The role of plasminogen activator inhibitor-1 (PAI-1) in vascular smooth muscle cell (VSMC) apoptosis mediated by plasminogen activation was studied with the use of aorticVSMC derived from mice with deficiency of PAI-1 (PAI-1 (-/-) ), tissue-type (t-PA (-/-) ) or urokinase-type (u-PA (-/-) ) plasminogen activator or from wildtype (WT) mice with corresponding genetic background. Plasminogen incubated with confluent VSMC was activated in a concentration-dependent and saturable manner for all four cell types, with maximal activation rates that were comparable for WT, u-PA (-/-) and t-PA (-/-) cells, but about two-fold higher for PAI-1 (-/-) cells. Plasminogen activation was impaired by addition of the lysine analogue 6-aminohexanoic acid, and by addition of t-PA and u-PA neutralizing antibodies, suggesting that it depends on binding to cell surface COOH-terminal lysine residues, and on plasminogen activator activity. Morphological alterations consistent with apoptosis were observed much earlier in PAI-1 (-/-) than in WT VSMC. Without addition of plasminogen, the apoptotic index was similar for all four cell types, whereas after incubation with physiological plasminogen concentrations, it was greater in PAI-1 (-/-) VSMC, as compared to WT, t-PA (-/-) or u-PA (-/-) VSMC. Furthermore, the apoptotic rate paralleled the release of plasmin. Thus, plasmin-mediated apoptosis of VSMC occurs via plasminogen activation by either t-PA or u-PA and is impaired by PAI-1.
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PMID:Plasminogen activator inhibitor-1 impairs plasminogen activation-mediated vascular smooth muscle cell apoptosis. 1708 Feb 25

The effects of hypotensive agents (captopril, enalaprilate, and lisinopril) on the activities of components of the fibrinolytic system (FS) and the effects of antifibrinolytic agents (6-aminohexanoic acid (6-AHA) and tranexamic acid (t-AMCHA)) on the activities of angiotensin converting enzyme (ACE) were studied in vitro. Enalaprilate did not affect the FS activity. Captopril considerably inhibited the amidase activities of urokinase (u-PA), plasminogen tissue activator (t-PA), and plasmin ([I]50 (2.0-2.6) +/- 0.1 mM), and the activation of Glu-plasminogen affected by t-PA and u-PA ([I]50 (1.50-1.80) +/- 0.06 mM), which may be due to the presence of a mercapto group in the inhibitor molecule. Lisinopril did not affect the amidase activities of FS enzymes, but stimulated Glu-plasminogen and u-PA activation and inhibited activation of t-PA-fibrin-bound Glu-plasminogen ([I]50 (12.0 +/- 0.5) mM). Presumably, these effects can be explained by the presence in lisinopril of a Lys side residue, whose binding to lysine-binding Glu-plasminogen centers resulted, on the one hand, in the transformation of its closed conformation to a semi-open one and, on the other hand, in its desorption from fibrin. Unspecific inhibition of the activity of ACE, a key enzyme of the renin-angiotensin system, in the presence of 6-AHA and t-AMCHA ([I]50 10.0 +/- 0.5 and 7.5 +/- 0.4 mM, respectively) was found. A decrease in the ACE activity along with the growth of the fibrin monomer concentration was revealed. The data demonstrate that, along with endogenous mediated interactions, relations based on the direct interactions of exogenous inhibitors of one system affecting the activities of components of another system can take place.
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PMID:[The in vitro cross-effects of inhibitors of renin-angiotensin and fibrinolytic systems on the key enzymes of these systems]. 1869 19

Earlier studies of addition of naturally sulfated polysaccharides including unfractionated heparin showed a significant enhancement of the in-vitro activation of glutamic plasminogen (Glu-Plg) by tissue plasminogen activator (t-PA) or urokinase plasminogen activator (u-PA). However, supplementing of physiological concentration of NaCl (0.9%) to the buffer reversed the enhancement. To overcome this reversal attempts were made to oversulfate the compounds and re-evaluate their biological properties. Chondroitin-6-sulfate (N-2) was oversulfated using chlorosulfonic acid-pyridine complex and isolated as the sodium salt. Infrared and H-NMR studies of the oversulfated compound showed introduction of new sulfate groups with the formation of 60% of chondroitin-4-6-disulfate. In-vitro studies were conducted on comparing the effect of oversulfated chondroitin-6-sulfate (S-2) with native compound (N-2) and unfractionated heparin in enhancing the activation of Glu-Plg by t-PA or u-PA using 0.05 mol/l Tris buffer (pH 7.3) containing 0.9% of NaCl. The enhancement of activation of Glu-Plg by t-PA or u-PA was measured by formation of plasmin using H-D-Glu-Phe-Lys-pNA (S-2403) as the substrate. The activation by t-PA was enhanced two-fold by 2.86 microg/ml of S-2, 4-6-fold by addition of 32.4 mmol/l of lysine or 5.4 mmol/l of 6-aminohexanoic acid (6-AH) and 14-16-fold enhancement by addition of both S-2 and lysine or S-2 and 6-AH showing a synergistic effect, whereas unfractionated heparin alone gave no enhancement and in conjunction with lysine or 6-AH gave no additional enhancement. Similar studies using u-PA in place of t-PA gave identical results. During the activation of Glu-Plg to plasmin, lysine plasminogen (Lys-Plg) is reported to be an intermediate. Therefore we investigated the role of S-2, lysine and 6-AH in the activation of Lys-Plg to plasmin. The results showed that S-2 enhanced this activation, whereas lysine or 6-AH which were active in enhancing the activation of Glu-Plg were not active using Lys-Plg indicating that the site of enhancement by lysine or 6-AH was during the initial phase. Double reciprocal plot of Glu-Plg activation by t-PA with or without S-2 and lysine showed no change in Km but a 10-fold increase of Kcat suggesting a template mechanism for the attenuation when both cofactors are used.
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PMID:Mechanism of the synergistic effect between oversulfated chondroitin-6-sulfate and lysine or 6-aminohexanoic acid in enhancing the in-vitro activation of glutamic plasminogen by tissue plasminogen activator or urokinase. 2044 43


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