Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.4.21.7 (plasmin)
9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Calcium-replete thrombospondin has been purified from outdated platelets using heparin-Sepharose affinity chromatography, gelatin-Sepharose to remove fibronectin, and gel filtration to eliminate low-molecular-weight heparin-binding proteins. Edman degradation of six different preparations revealed the amino-terminal sequence of thrombospondin (TSP) to be Asn-Arg-Ile-Pro-Glu-Ser-Gly-Gly-Asp-Asn-Ser-Val-Phe-. This sequence was obtained in initial yields as high as 85%, indicating that no blocked chains are present. Cleavage of calcium-replete TSP with thermolysin or plasmin results in the production of relatively stable fragments. Chromatography of these digests on heparin-Sepharose followed by elution with 0.6 M NaCl affords purification of an Mr 25,000 fragment from the thermolysin digest and an Mr 35,000 fragment from the plasmin digest. The binding of these fragments to heparin-Sepharose does not require divalent metal ions. Neither fragment is disulfide-bonded to other fragments present in the digests. The heparin-binding domains from both digests have similar amino acid compositions and their tryptic peptide maps on high performance liquid chromatography are identical with the exception of one peptide unique to each fragment. Automated Edman degradation in a vapor-phase sequenator of the thermolytic heparin-binding domain electroeluted from sodium dodecyl sulfate-gels indicates that the heparin-binding domain resides at the amino terminus of the Mr 180,000 TSP peptide chain.
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PMID:Isolation and characterization of a heparin-binding domain from the amino terminus of platelet thrombospondin. 623 12

The kinetics of the thrombin-induced release of fibrinopeptides from several variants of human fibrinogen, and from the plasmin digestion fragment E thereof, have been studied by using an HPLC technique to separate the reaction products. The data were analyzed in terms of a Michaelis-Menten mechanism in which the A alpha and B beta chains compete for thrombin. Phosphorylation of Ser-3 of the A alpha chain appears to increase the rate of release of the corresponding phosphorylated peptide A from fibrinogen, due to enhanced binding of thrombin (lower value of the Michaelis-Menten constant KM). However, phosphorylation does not affect the rate of release of the unphosphorylated A or B peptides. Increase in the length of the gamma chain (at the C-terminus) does not affect the rate of release of any of the fibrinopeptides. The rate of release of the A peptide from fragment E (which is devoid of the B peptide) is similar to that for the complete fibrinogen molecule. These results are in agreement with an earlier conclusion [Martinelli, R. A., & Scheraga, H. A. (1980) Biochemistry 19, 2343] that the A alpha and B beta chains behave independently in their competition for thrombin; i.e., the hydrolyzable Arg-Gly bonds of the A alpha and B beta chains are both accessible to thrombin.
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PMID:Comparison of structures of various human fibrinogens and a derivative thereof by a study of the kinetics of release of fibrinopeptides. 623 19

The effect of heparin on non-stabilized fibrin hydrolysis by plasmin was investigated. Using analytical centrifugation in the presence of heparin, the existence of a high molecular weight fraction (sedimentation coefficient 17S) was demonstrated. Electrophoretic analysis revealed the presence of less degradable early, intermediate and late fibrin hydrolysis products. It is concluded that the molecular mechanisms of these effects are due to the direct action of heparin on the fibrin-monomer molecule which provides for the inhibition of peptide side chains localized between residues 15 Gly-53 Lys in the NH2-terminal part of the B beta-chain. The universal mechanisms underlying the anti-fibrinolytic activity of high molecular weight inhibitors of fibrin polymerization and aggregation are discussed.
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PMID:[Antifibrinolytic effect of heparin]. 624 Feb 83

Protein Z was purified from human plasma by a four-step procedure which included barium citrate adsorption, ammonium sulfate fractionation, DEAE-Sepharose chromatography, and blue agarose chromatography with a yield of 20%. It is a 62,000 mol wt protein with an extinction coefficient of 12.0. The concentration of Protein Z in pooled, citrated plasma is 2.2 micrograms/ml and its half-life in patients starting warfarin anticoagulation therapy is estimated to be less than 2.5 d. The NH2-terminal sequence is Ala-Gly-Ser-Tyr-Leu-Leu-(Gla)-(Gla)-Leu-Phe-(Gla)-Gly-Asn-Leu. Neither Protein Z nor its cleavage products, which were obtained by treatment of Protein Z with thrombin or plasmin, incorporated [3H]diisopropyl fluorophosphate. The physiological function of Protein Z remains unknown.
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PMID:Human Protein Z. 670 12

Fibrinopeptides A and B were removed from purified human fibrinogen by bovine thrombin, whereas the snake venom protease batroxobin only split fibrinopeptide A from fibrinogen. Aggregation of the resulting desAB- and desA-fibrin monomers was evaluated by recording the turbidity of incubation mixtures. Fibrin assembly was strongly accelerated by increasing the calcium concentration from 10(-5) to 10(-3) M. Fragment D was obtained from fibrinogen by proteolytic degradation with plasmin in the presence of Ca2+. At a 4-fold molar concentration relative to fibrinogen, fragment D dramatically inhibited fibrin polymerization at up to 10(-4) M Ca2+. This anticlotting activity was, however, much less pronounced at 10(-3) M Ca2+. The thrombin clotting time, measured on human plasma, was prolonged by fragment D in a dose-dependent manner. In citrate-containing plasma, the fibrinogen clotting was significantly delayed by an equimolar concentration of fragment D. In barium sulfate-adsorbed oxalated plasma, containing 2.5 mM Ca2+, the same amount of fragment D hardly affected fibrin polymerization. We conclude that fragment D has no important anticlotting effect under physiological conditions. The synthetic peptide Gly-Pro-Arg, corresponding to the amino-terminal sequence of the fibrin alpha-chain, inhibited aggregation of both desA-fibrin and desAB-fibrin at 10(-3) M Ca2+. The inhibition of desAB-fibrin polymerization by Gly-Pro-Arg was abolished at 10(-5) M Ca2+. In addition, Gly-Pro-Arg depressed the anticlotting activity of fragment D at low calcium concentration. An analogue of the amino-terminus of fibrin beta-chain, Gly-His-Arg, strongly accelerated aggregation of desA-fibrin monomers, but only moderately enhanced polymerization of desAB-fibrin monomers at 10(-5) M Ca2+, both in the presence and in the absence of fragment D. This activating effect of Gly-His-Arg was abolished at 10(-3) M Ca2+. It is suggested that the binding of calcium, Gly-His-Arg, and possibly also Gly-Pro-Arg, induces a conformational change in fibrin monomers and thus accelerates the polymerization process.
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PMID:Inhibition of fibrin polymerization by fragment d is affected by calcium, Gly-Pro-Arg and Gly-His-Arg. 682 84

Porcine tissue plasminogen activator has been purified from delipidized heart tissue by affinity adsorption to fibrin. A crude fraction is prepared from an acid tissue extract by precipitation with ammonium sulphate. The tissue activator of this fraction is isolated by adsorption on fibrin and elution with KSCN. The procedure also includes chromatography on arginine-Sepharose and two gel-filtration steps. The final product has a specific activity of 250 000 IU/mg (+/- 16 000) as compared to an international urokinase reference preparation. The yield calculated from the active ammonium sulphate precipitate is about 28%. An approx. 7 000-fold increase of specific activity is obtained, most of which is achieved in the fibrin step. The native tissue plasminogen activator consists of a single chain molecule with a molecular weight of 64 000 as measured by SDS-polyacrylamide gel electrophoresis. In a previous report, it was claimed that the activator is composed of two disulphide-connected polypeptide chains. These results were due to a preparation artefact, caused by proteolytic activity present in the tissue extracts. The introduction of the protease inhibitor aprotinin and 6-amino-hexanoic acid in the purification procedure has abolished the effect of the protease contaminant, leading to the production of a one-chain activator. Treatment with plasmin transforms the native, one-chain tissue activator into a variant composed of two chains of about equal size (Mr 32 000) connected by disulphide bonding. This modified activator is indistinguishable from the one obtained at insufficient protection against proteolytic enzymes. The cleavage by plasmin causes about an 8-fold increase of amidolytic activity as measured on H-D-Val-Gly-Arg-p-nitroanilide. The fibrinolytic activity as measured by clot lysis in only slightly increased. The physiological significance of the cleavage is discussed.
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PMID:Purification and identification of two structural variants of porcine tissue plasminogen activator by affinity adsorption on fibrin. 689 Dec 67

The method for preparing thrombin-degranulated platelets has been modified to avoid the use of plasmin or successive treatments with small amounts of thrombin, while still achieving more than 90% release of platelet amine storage granule contents. It was necessary to prevent the fibrinogen released from the platelets during thrombin treatment from forming an insoluble fibrin mesh that could trap the platelets and hinder their deaggregation. To accomplish this we have treated rabbit platelets with 0.73 U/ml of thrombin for 1 min in the presence of the synthetic peptide, Gly-Pro-Arg-Pro, which prevents the polymerization of fibrin molecules. We have demonstrated that it also prevents 125I, initially added as 125I-fibrinogen, from associating with the platelets in a form that was not removed by centrifuging and washing during the preparation of thrombin-degranulated platelets, and we infer that products formed from the fibrinogen released from the platelets would also be prevented from associating with them. Thrombin-degranulated platelets prepared by this method have lost 92% of their granule contents and they can be washed and resuspended. These platelets aggregate normally upon stimulation with thrombin, adenosine diphosphate (ADP), or arachidonate. Thus, Gly-Pro-Arg-Pro is useful in preparing thrombin-degranulated platelets for studying platelet reactions without the complicating effects of released materials such a ADP and fibrinogen.
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PMID:The use of the synthetic peptide, Gly-Pro-Arg-Pro, in the preparation of thrombin-degranulated rabbit platelets. 707 21

Highly purified fibrinogen-fibrin related antigen (FR-antigen) was isolated with good recovery from 1.0--2.0 ml of human plasma, by immuno-affinity chromatography with antibody specific for fibrinogen and fibrin, and plasmin degradation products X, Y, D and D-D dimer. In FR-antigen from defibrinating patients there was evidence for thrombin activity alone (mainly disseminated cancer) or both plasmin and thrombin (mainly abruptio placentae). Thus, the molar ratio of N-terminal Gly-Tyr in the FR-antigen of 18 of 20 patients strongly suggested thrombin activity (95th percentile). In addition, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) on unreduced samples frequently showed bands similar in mol wt to fragments X, Y and D, and in the reduced samples A alpha and B beta chain degradation, both indicating plasmin activity. 'N-terminal beta chain Ala' was elevated in the antigen of four of 20 patients, also suggesting plasmin activity (99th percentile). Combined thrombin, plasmin and factor-XIII activity, as shown with high levels of serum FR-antigen (greater than 10 mg/dl). In some defibrinating patients, especially those with disseminated cancer, heterogeneity of unreduced FR-antigen and A alpha chain degradation, both indicators of mild plasmin-like activity which are commonly seen in normals, were absent.
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PMID:Isolation of fibrinogen-fibrin related antigen from human plasma by immuno-affinity chromatography: its characterization in normal subjects and in defibrinating patients with abruptio placentae and disseminated cancer. 737 21

We have developed a method for producing fibrinogen-coated, reversibly adhesive, lecithin/cholesterol vesicles. In this method, fibrinogen, which is acylated in the presence of preformed vesicles, spontaneously incorporates into vesicular membranes. The degree of incorporation is a function of the extent of acylation of the protein. Fibrinogen-coated vesicles aggregate in the presence of thrombin, a consequence of intervesicular fibrin formation. The rate and extent of thrombin-initiated aggregation depend on the fibrinogen surface concentration. Once aggregated, fibrin-coated vesicles can be dissociated by plasmin and by agents that disrupt intervesicular fibrin dimerization such as heparin and the tetrapeptide Gly-Pro-Arg-Pro. Fibrinogen-coated vesicles can be made to bind avidly to the surface of solution phase fibrin matrices and can be incorporated into solution phase fibrin clots. Fibrinogen-coated vesicles also bind to activated platelets. We propose that fibrinogen-coated vesicles will have practical applications as biomimetic hemostatic agents and as vehicles for the fibrin-specific targeting of drugs and other molecules.
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PMID:Preparation and characterization of fibrinogen-coated, reversibly adhesive, lecithin/cholesterol vesicles. 762 27

The three-dimensional structure of the basic pancreatic trypsin inhibitor (BPTI) contains four internal water molecules, which form a total of nine intermolecular hydrogen bonds with the BPTI polypeptide chain. To investigate the effect of such internal hydration on protein structure and stability, we displaced one of the internal water molecules in a recombinant BPTI analogue, BPTI(G36S), in which Gly 36 is replaced by serine. The replacement of a water molecule by the seryl side chain was established by the absence of the protein-water nuclear Overhauser effects (NOE) that had been attributed to the water molecule near Gly 36 in wild-type BPTI and by the presence of new, intramolecular NOEs to the hydroxyl proton of Ser 36. BPTI(G36S) has slightly reduced thermal stability compared to BPTI, corresponding to a destabilization by delta (delta G) approximately 0.7 kcal/M in 6 M guanidinium hydrochloride solution. Additionally, the stabilities of the complexes formed between BPTI(G36S) and trypsin, plasmin, or kallikrein are significantly reduced when compared to the corresponding complexes with wild-type BPTI.
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PMID:Designed replacement of an internal hydration water molecule in BPTI: structural and functional implications of a glycine-to-serine mutation. 768 91


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