Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.73 (urokinase-type plasminogen activator)
 10,685 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Pro-Gly-ArgCH2Cl, a reagent corresponding to the C-terminal sequence generated in plasminogen on activation by urokinase (EC 3.4.99.26) and probably by other plasminogen activators, was prepared. Pro-Gly-ArgCH2Cl was effective in the inactivation of urokinase at the 10(-6) M level (Ki 68 micrometers and k2 0.47 min-1). In contrast, only a slow inactivation was obtained by 10(-2) M N-tosyllysine chloromethyl ketone. Glu-Gly-ArgCH2Cl, N,N-dimethylaminonaphthalene-5-sulfonyl-Glu-Gly-ArgCH2Cl, and Ac-Gly-Gly-ArgCH2Cl were more reactive than Pro-Gly-ArgCH2Cl against urokinase by factors of 25, 6, and 3, respectively. The effectiveness of arginine chloromethyl ketones as affinity labels is highly dependent on binding in the S2 and S3 sites, thus sequence variations in the reagents exhibited differences in reactivity of up to four orders of magnitude. The most effective reagents had Gly in P2. Ac-Gly-Gly-ArgCH2Cl inactivates urokinase 50 times more rapidly than it does plasmin, thus providing a means of distinguishing the activity of plasmin from its activating protease whereas urokinase is almost inert to Ala-Phe-LysCH2Cl, a reagent which inactivates plasmin at the 10(-7) M level.
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PMID:The susceptibility of urokinase to affinity labeling by peptides of arginine chloromethyl ketone. 46 6

Fibrinogen-fibrin-related antigen (FR antigen) was isolated from as little as 1 ml of human plasma by immuno-affinity chromatography with agarose-bound antibody to human fibrinogen. N-terminal analysis was performed to determine the nature and extent of proteolytic degradation of the FR antigen in patients with disseminated intravascular coagulation and in normal subjects. Thrombin cleavage of the A- and B-peptides from fibrinogen in vitro was monitored by the appearance of N-terminal glycine, and an increase in glycine was shown in the FR antigen of patients with disseminated intravascular coagulation. As plasmin progressively degraded fibrinogen, increases in N-terminal alanine, aspartic acid and lysine were observed, corresponding to the known plasmin-cleavage points of fibrinogen; increases in these N-terminal amino acids were also found in the patients' FR antigen. Thrombin treatment in vitro was used to remove fibrinopeptide A (N-terminal alanine) from the samples and to reflect specifically the N-terminal alanine at the plasmin-cleavage point (Arg-42-Ala-43) of the B beta-chain on assay; this alanine was increased progressively in the FR antigen of a patient during urokinase therapy, and was high in other patients when the FR antigen was examined by this procedure.
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PMID:Quantitative N-terminal analysis of fibrinogen-fibrin-related antigen [FR antigen] from human plasma. 54 36

Synthetic procedures have been developed for the preparation of peptides of arginine chloromethyl ketone and applied in the preparation of affinity labels which correspond to the -Pro-Phe-Arg- C terminus of bradykinin, a physiological cleavage site of kallikrein in kininogen. Two such reagents, Ala-Phe-ArgCH2C1 and Pro-Phe-ArgCH2C1, proved to be highly effective as well as selective affinity labels for human plasma kallikrein. For example, Pro-Phe-ArgCH2C1 inactivates plasma kallikrein 50% in 24 min at a concentration of 2 x 10(-8)M, while other trypsin-like proteases are less susceptible in inactivation than kallikrein, differing by a factor of 48 for plasmin and factors of 10(2)-10(5) for factor Xa, thrombin, and urokinase. The affinity of human plasma kallikrein for Ala-Phe-ArgCH2C1 (Ki = 0.078 micron) is about 60 times that for Ala-Phe-LysCH2C1(Ki = 4.9 micron), whereas human plasmin exhibits about the same affinity for the former affinity label (Ki = 1.3 micron) as for the latter (Ki = 0.83 micron). The rate constants for the irreversible step of the affinity labeling reaction, k2, are similar for affinity labels tested with the individual proteases: 0.35 min-1 for plasma kallikrein and 0.18 min-1 for plasmin.
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PMID:Synthesis of peptides of arginine chloromethyl ketone. Selective inactivation of human plasma kallikrein. 72 86

In a previous study, it was shown that fibrin fragment E-2 selectively promotes the activation of plasminogen by pro-urokinase (pro-UK) [Liu, J., & Gurewich, V. (1991) J. Clin. Invest. 88, 2012-2017]. In this study, the kinetics of this promotion by fragment E-2 was studied. Alanine-158-rpro-UK (A-pro-UK), a recombinant plasmin-resistant mutant, was used in order to avoid interference by UK generation during the reaction. In some experiments, pro-UK was substituted in order to validate the mutant as a surrogate. In the presence of a range of concentrations (0-20 microM) of fragment E-2, a linear promotion of the catalytic efficiency of A-pro-UK against native Glu-plasminogen was seen which was 245.5-fold at the highest concentration of fragment E-2 and 450-fold at the highest ratio of E-2/plasminogen used. The promotion was largely a function of an increase in kcat, since fragment E-2 induced a less than 10-fold reduction in KM (8.50-1.40 microM). In contrast to this ligand, epsilon-aminocaproic acid (EACA) induced a biphasic promotion of the activation of Glu-plasminogen which was only 18-fold at maximum. Fragment E-2 did not promote the activation of Lys-plasminogen, but the catalytic efficiency of A-pro-UK was 19.7-fold greater against the open Lys-form than against the closed Glu- form of plasminogen. Fragment E-2 had no effect on the amidolytic activity of A-pro-UK or pro-UK, suggesting that the promotion of their activities was indirect and related to a fragment E-2-induced conformational change in Glu-plasminogen.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Fragment E-2 from fibrin substantially enhances pro-urokinase-induced Glu-plasminogen activation. A kinetic study using the plasmin-resistant mutant pro-urokinase Ala-158-rpro-UK. 138 27

N-desulphated heparin, partially N-acylated on average with three oleoyl chains per molecule, inhibits the amidolytic activity of plasmin (IC50 16 nM) and urokinase (IC50 10mM) when assayed on N-p-tosyl-Gly-Pro-Lys-4-nitroanilide and benzoyl-Ala-Gly-Arg-4-nitroanilide substrates respectively. N-desulphated heparin is not inhibitory. This effect requires the covalent binding of oleoyl residues to heparin and it decreases with increasing concentration of Tris-HCl and non-ionic detergents.
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PMID:N-oleoyl heparin inhibits the amidolytic activity of plasmin and urokinase. 138 49

The role of glycosylation on the enzymatic properties of single chain urokinase-type plasminogen activator (scu-PA) was investigated by site-specific mutagenesis of the glycosylated Asn-302 residu to Gln. In addition, the role of the NH2-terminal polypeptide chain and of the Cys-148 to Cys-279 interchain disulphide bond on the activity of non-glycosylated scu-PA was investigated. Therefore, variants of recombinant scu-PA (rscu-PA) were produced by transfecting Chinese hamster ovary cells with cDNA encoding rscu-PA N302Q (rscu-PA with Asn-302 to Gln mutation), rscu-PA C279A,N302Q (rscu-PA with Cys-279 to Ala and Asn-302 to Gln mutations) or rscu-PA del(N2-F157)C279A,N302Q (rscu-PA C279A,N302Q with deletion of Asn-2 through Phe-157). These mutants were purified to homogeneity from conditioned cell culture medium and were obtained essentially as single chain molecules with specific activities on fibrin plates of (mean +/- S.E.; n = 6) 45,000 +/- 5000. IU/mg, 19,000 +/- 800 IU/mg and < or = 100 IU/mg for rscu-PA N302Q, rscu-PA C279A,N302Q and rscu-PA del(N2-F157)C279A,N302Q, respectively, as compared to 64,000 +/- 2600 IU/mg for wild-type rscu-PA obtained in the same expression system. Plasmin quantitatively converts rscu-PA N302Q and rscu-PA C279A,N302Q to amidolytically active two-chain derivatives with a specific activity of 56,000 IU/mg and 32,000 IU/mg, respectively, as compared to 75,000 IU/mg for wild-type rscu-PA. Plasminogen activation as a function of time was comparable for rscu-PA N302Q and wild-type rscu-PA, and somewhat slower for rscu-PA C279A,N302Q. In a human plasma milieu in vitro, consisting of a 125I-fibrin labeled plasma clot submerged in plasma, 50 percent clot lysis in 2 h required 2.2 micrograms/ml rscu-PA N302Q and 6.0 micrograms/ml rscu-PA C279A,N302Q, as compared to 3.2 micrograms/ml wild-type rscu-PA. In contrast, rscu-PA del(N2-F157)C279A,N302Q was not converted to an amidolytically active two chain derivative by plasmin, and did not induce significant plasminogen activation in purified systems or clot lysis in a human plasma milieu. Following bolus injections in hamsters, the initial half-lives (1.8-2.6 min) and the plasma clearances (0.6-1.5 ml min-1) were comparable for wild-type rscu-PA and for the three rscu-PA mutants. These results suggest that the fibrinolytic activity in a plasma milieu in vitro and the in vivo turnover of rscu-PA are not markedly affected by the absence of carbohydrate.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Biochemical properties of recombinant mutants of nonglycosylated single chain urokinase-type plasminogen activator. 139 Sep 10

Urokinase (u-PA) proteolytically cleaves both human plasma (pFn) and cellular (cFn) dimeric fibronectin (M(r) 440,000) into four major polypeptides of approximately M(r) 210,000, 200,000, 25,000, and 6,000. Amino acid sequence analysis of the polypeptide fragments indicated that the enzymatic cleavage of Fn occurs at two sites: 1) between an arginine/alanine peptide bond located C-terminal to residue 259; this cleavage liberates the N-terminal M(r) 25,000 fragment and the M(r) 210,000 and M(r) 200,000 polypeptides derived from the A and B chains of Fn, respectively; and 2) between an arginine/threonine peptide bond located C-terminal to residue 2,299, thereby yielding an M(r) 6,000 dimeric fragment containing the C-terminal interchain disulfide bonds. Predigestion of Fn with u-PA increased the molecule's vulnerability to further attack by the enzymes plasmin and cathepsin D. These data provide further biochemical evidence for the proteolytic cleavage of fibronectin by plasminogen activators and substantiate that u-PA digestion of Fn may be an initial event in the local degradation of the extracellular matrix by malignant cells, possessing elevated levels of these enzymes.
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PMID:Localization of the cleavage sites on fibronectin following digestion by urokinase. 146 74

Linear tri- and tetrapeptide precursors of 2,5-piperazinedione were prepared and their conversion to spirocyclic dipeptidase enzymes, the spirocyclic dipeptides (SpDp) were generated from the precursors by a two-step mechanism consisting in the proteolytic release of the C-terminal dipeptide ethyl ester and its subsequent spontaneous cyclization. After intraperitoneal administration of urokinase and Ac-Leu-Lys-Gly-Acp-OEt, a SpDp precursor targeted to endogenous plasmin, or the administration of the activated Hageman factor fragment and Ac-Leu-Arg-Ala-Acp-OEt, a SpDp precursor, targeted to endogenous kallikrein, the generated corresponding C-terminal dipeptide ethylester intermediates and SpDp, cyclo(Gly-Acp) and cyclo (Ala-Acp), respectively, were detected in the blood serum of C57B1 mice. Suppression of partial amnesia induced by sodium nitrite was observed in rats where it was subcutaneously administered with H-Leu-Ala-Acp-OEt, a peptide precursor of alaptide, the active SpDp, i.e. cyclo(1-amino-1-cyclopentanecarbonyl-L-alanyl).
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PMID:Two-step generation of spirocyclic dipeptides from linear peptide ethyl ester precursors. 153 Sep 83

The contribution of the NH2-terminal polypeptide chain and of the Cys148-Cys279 interchain disulphide bond to the enzyme activity of urokinase-type plasminogen activator (u-PA) was studied using site-specific mutagenesis. Recombinant single-chain u-PA (rscu-PA) variants were produced by transfecting Chinese hamster ovary cells with cDNA encoding des(Asn2-Phe157)rscu-PA (rscu-PA with deletion of Asn2-Phe157), [Ala279]rscu-PA (rscu-PA with Cys279----Ala mutation) or des(Asn2-Phe157)[Ala279]rscu-PA [des(Asn2-Phe157)rscu-PA with Cys279----Ala mutation]. Des(Asn2-Phe157)rscu-PA, [Ala279]rscu-PA and des(Asn2-Phe157)[Ala279]rscu-PA, purified from conditioned cell culture medium, were obtained as nearly homogeneous single-chain molecules with Mr approximately 30,000, 54,000 and 30,000, and specific fibrinolytic activities on fibrin plates of (mean +/- SD; n = 3) 860 +/- 150 IU/mg, 43.0 +/- 2.5 IU/micrograms and 240 +/- 20 IU/mg, respectively, compared to 69.0 +/- 4.3 IU/micrograms for wild-type rscu-PA obtained in the same expression system. The plasminogen activating potential in a buffer milieu of [Ala279]rscu-PA was somewhat lower than that of rscu-PA, but that of both deletion mutants was virtually abolished. In a human plasma milieu in vitro, consisting of a radiolabelled human plasma clot submerged in plasma, 50% clot lysis in 2 h required 6.5 micrograms/ml [Ala279]rscu-PA or 3.4 micrograms/ml rscu-PA, whereas with both deletion mutants no significant clot lysis was observed with up to 16 micrograms/ml. Treatment of [Ala279]rscu-PA or rscu-PA with plasmin resulted in quantitative conversion to two-chain molecules and was associated with an increase in specific amidolytic activity from about 600 IU/mg to 62.5 IU/micrograms for [Ala279]rscu-PA as compared to an increase from about 0.3 IU/micrograms to 75.0 IU/micrograms for rscu-PA. In contrast, no significant amidolytic activity could be generated by treatment of des(Asn2-Phe157)rscu-PA or des(Asn2-Phe157)[Ala279]rscu-PA with plasmin. The u-PA B-chain, isolated from plasmin-treated [Ala279]rscu-PA, had enzymic properties which were comparable to those of rtcu-PA, with respect to specific fibrinolytic activity, amidolytic activity, kinetics of plasminogen activation and clot-lysis activity in a human plasma milieu in vitro. Following bolus injection into hamsters, the plasma clearances were comparable (0.7-1.1 ml/min) for wild-type rscu-PA and for the three truncated rscu-PA mutants.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Biochemical properties of recombinant single-chain urokinase-type plasminogen activator mutants with deletion of Asn2 through Phe157 and/or substitution of Cys279 with Ala. 153 68

Plasminogen activator inhibitor-1 (PAI-1) is a specific inhibitor of the serine proteases tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA). To systematically investigate the roles of the reactive center P1 and P1' residues in PAI-1 function, saturation mutagenesis was utilized to construct a library of PAI-1 variants. Examination of 177 unique recombinant proteins indicated that a basic residue was required at P1 for significant inhibitory activity toward uPA, whereas all substitutions except proline were tolerated at P1'. P1Lys variants exhibited lower inhibition rate constants and greater sensitivity to P1' substitutions than P1Arg variants. Alterations at either P1 or P1' generally had a larger effect on the inhibition of tPA. A number of variants that were relatively specific for either uPA or tPA were identified. P1Lys-P1'Ala reacted 40-fold more rapidly with uPA than tPA, whereas P1Lys-P1'Trp showed a 6.5-fold preference for tPA. P1-P1' variants containing additional mutations near the reactive center demonstrated only minor changes in activity, suggesting that specific amino acids in this region do not contribute significantly to PAI-1 function. These findings have important implications for the role of reactive center residues in determining serine protease inhibitor (serpin) function and target specificity.
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PMID:Saturation mutagenesis of the plasminogen activator inhibitor-1 reactive center. 155 96


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