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:3.4.21.6 (thromboplastin)
13,278 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A strong inhibitor of human Hageman factor fragment (HFf, beta-factor XIIa) and bovine trypsin was isolated from pumpkin (Cucurbita maxima) seed extracts by acetone fractionation, by chromatography on columns of diethyl-aminoethylcellulose and carboxylmethyl-Sephadex C-25, and by Sephadex G-50 gel filtration. Pumpkin seed Hageman factor inhibitor (PHFI) is unusual in its lack of inhibition of several other serine proteinases tested--human plasma, human urinary, and porcine pancreatic kallikreins, human alpha-thrombin, and bovine alpha-chymotrypsin. Human plasmin and bovine factor Xa are only weakly inhibited. PHFI also inhibits the HFf-dependent activation of plasma prekallikrein and clotting of plasma. Other properties of PHFI are a pI of 8.3, 29 amino acid residues, amino-terminal arginine, carboxyl-terminal glycine, 3 cystine residues, undetectable sulfhydryl groups and carbohydrate, and arginine at the reactive site. The minimum molecular weight of PHFI is 3268 by amino acid analysis. PHFI may be the smallest protein inhibitor of trypsin known.
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PMID:Pumpkin seed inhibitor of human factor XIIa (activated Hageman factor) and bovine trypsin. 621 35

A 42-yr-old woman with systemic lupus erythematosus without bleeding diathesis developed a prolonged activated partial thromboplastin time that was not corrected by normal plasma. An inhibitor that acted rapidly and inactivated 0.5 U/ml plasma thromboplastin antecedent (PTA, factor XI) at a 1:200 plasma dilution was demonstrated. In addition to a low titer of PTA (less than 0.01 U/ml), plasma assayed at 20-fold dilution also showed low titers of Hageman (factor XII, 0.02 U/ml), Fletcher (plasma prekallikrein, 0.02 U/ml), and Fitzgerald (high molecular weight kininogen, less than 0.01 U/ml) factors. The titer of these factors, except PTA, returned to normal upon further plasma dilution or upon removal of the inhibitor by protein A adsorption. Thus, the inhibitor appeared to interfere with these clotting factor assays, possibly by inactivating PTA in the substrate plasmas in the test system. Its specificity was further confirmed. The inhibitor did not interfere with surface-induced proteolytic cleavage of Hageman factor. Surface-induced generation of plasma kallikrein activity (amidolysis of H-D-pro-phe-arg-pNa and cold-promoted factor VII activity enhancement) requires only Hageman, Fletcher, and Fitzgerald factors and was normal. Reactions requiring all 4 contact phase factors, including PTA, such as surface-induced generation of plasmin activity (amidolysis of H-D-val-leu-lys-pNa) and activated Christmas factor (factor IXa) activity, were defective. Furthermore, the inhibitor bound to agarose-protein A inactivated and removed PTA selectively from normal plasma. The inhibitor was an IgG-lambda autoantibody that precipitated PTA. The inactivated activated PTA (factor XIa) without the requirement for an additional cofactor. Furthermore, it inhibited surface-induced activation of PTA by interfering with its proteolytic cleavage upon glass surface exposure and with its binding onto the reactive surfaces.
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PMID:A unique precipitating autoantibody against plasma thromboplastin antecedent associated with multiple apparent plasma clotting factor deficiencies in a patient with systemic lupus erythematosus. 642 50

A new case of Fletcher factor (prekallikrein) deficiency is described. The patient did not have any abnormal bleeding tendency, but showed defective intrinsic thromboplastin production and reduced fibrinolytic system activity; he had no factor VIII, IX, XI and XII deficiencies. His plasma did not contain any detectable prekallikrein levels.
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PMID:Fletcher factor deficiency (Report of a new case). 655 74

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

The efficacy of low-molecular-weight heparin as a prophylactic agent was assessed in 150 consecutive patients over the age of 40 undergoing major abdominal surgery. Fifty of these patients received 1250 activated partial thromboplastin time (APTT) units of low-molecular-weight heparin every 12 hours: three developed isotopic deep vein thrombosis, which was confirmed by phlebography in two cases. The other 100 patients received a single injection of 1850 APTT units of low-molecular-weight heparin. Three of them developed isotopic deep vein thrombosis; phlebography failed to confirm the presence of thrombi in each case. None of the 150 patients studied died from fatal or contributory pulmonary emboli. Low-molecular-weight heparin was not associated with any increase in preoperative or postoperative bleeding. The effect of equal amounts of postoperative bleeding. The effect of equal amounts of low-molecular-weight heparin and unfractionated heparin on the coagulation mechanism during surgery was investigated in another 30 patients. The clotting assays and results of in-vivo platelet function tests indicated that both preparations produced similar effect. Intragroup comparisons, however, showed significant differences in the anti-factor Xa activity, lipoprotein lipase release, and plasma prekallikrein concentrations. A single injection of low-molecular-weight heparin daily is a convenient way of preventing deep vein thrombosis in high-risk patients undergoing major abdominal surgery.
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PMID:Low-molecular-weight heparin and prevention of postoperative deep vein thrombosis. 680 Apr 65

A case of cross-reacting material-negative Fletcher trait with additional partial deficiency of Hageman factor (HF, Factor XII) is described. Although the patient presented with a recent history of frequent epistaxis, he had no other personal or family history of a tendency toward bleeding or infection. Similar to other cases of Fletcher trait, his plasma showed a markedly prolonged partial thromboplastin time which could be corrected by prolonged incubation with the surface-activator kaolin. Surface-induced fibrinolysis, amidolysis of alpha-N-benzoyl-proline-L-phenylalanine-L-arginine-p-nitroanilide, and cold-promoted enhancement of factor VII activity, reactions requiring the presence in the plasma of fletcher factor (prekallikrein), in addition to Hageman factor and Fitzgerald factor (high-molecular weight kininogen), were also defective. In vivo chemotaxis of polymorphonuclear leukocytes and monocytes (Rebuck's skin window technique) in response to skin abrasions was defective, but was normal when diphtheria-tetanus toxoid was also applied. In vitro leukocyte chemotaxis (Boyden chamber technique) in response to normal or patient's own serum activated with zymosan was normal. Together with previous observations that kallikrein generated chemotactic activity, possibly via activation of C5, the present observations suggest that prekallikrein activation may be important for in vivo leukocyte chemotactic response to skin abrasion. The inheritance of Fletcher trait in this patient is unclear.l Although the father was an apparent heterozygote, the mother was completely normal for Fletcher factor procoagulant activity and antigen. The mild Hageman factor deficiency in the patient did not contribute significantly to the plasma defects described and was likely inherited from the father who had a low HF procoagulant activity.
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PMID:Severe Fletcher factor (plasma prekallikrein) deficiency with partial deficiency of Hageman factor (factor XII): report of a case with observation on in vivo and in vitro leukocyte chemotaxis. 691 94

Seventeen patients with a spectrum of immunologically-related disorders were studied before and immediately after plasma exchange (PE) for changes in coagulation factors, complement, immunoglobulins, and immune complex levels. Each PE replaced 50 per cent of the plasma volume with 5% albumin and saline. With PE, coagulation profiles indicated a decrease of 23 to 55 per cent in the levels of fibrinogen, Factors II, V, VII, VIII, IX, X, XI, XII, and Fletcher factor. Only minimal changes were noted in the prothrombin time and activated partial thromboplastin time. Most coagulation factors, except fibrinogen, returned to baseline by 48 hours. Following three PE/week, fibrinogen was reduced by 51 per cent; other factors were not significantly altered. C3 and C4 fell by 35 to 40 per cent with each PE; these approached baseline by 24 hours. Immunoglobulins (G,A,M) were reduced by 34 +/- 3,37 +/- 3 and 34 +/- 3 per cent, respectively. After three PE, the total immunoglobulins were decreased by 50 to 55 per cent. Five of eight patients who had three or more PE developed hypogammaglobulinemia (IgG less than 450 mg/dl). Immune complexes were reduced by 50 +/- 4 per cent with each PE. Multiple exchanges in five patients led to a greater reduction (80 +/- 6%). Thus PE was an effective means of reducing immune complexes but led to hypogammaglobulinemia and hypofibrinogenemia.
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PMID:Changes in coagulation factors, complement, immunoglobulins, and immune complex concentrations with plasma exchange. 706 8

Screening coagulation tests, coagulation factors, and components of fibrinolysis and kinin generation were examined in 21 healthy adult cats. Observed ranges for screening tests were: prothrombin time, 7.3 to 11.4 s; activated partial thromboplastin time, 10.6 to 14.9 s; and thrombin time, 10.7 to 18.9 s. Functional coagulation factors II, V, VII, VIII, IX, X, XI, and XII were assayed and expressed as percentage of normal. Although individual factors varied, the observed range for factors assayed was 37% to 208% of normal. Fibrinogen ranged from 50 to 165 mg/dl. Plasminogen and antithrombin III ranged from 50% to 200% and 89% to 111% of normal, respectively. Plasma kallikrein ranged from 0.3 to 3.9 mukat/L. Fibrin(ogen) degradation products and fibrin monomers were examined with variable and inconsistent results.
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PMID:Coagulation, fibrinolysis, and kinin generation in adult cats. 710 32

Normal newborn infants have a prolonged partial thromboplastin time compared to that of older infants or adults. This finding has been related to combined deficiencies of multiple clotting factors, with the exception of proaccelerin (factor V) and antihemophilic factor (factor VIII). The present study confirms the presence of decreased titers of Hageman factor (HF, factor XII), plasma prekallikrein, and high molecular weight kininogen during the neonatal period, as demonstrated in clotting assays; the degree of these relative deficiencies is usually such that only the low titer of HF appears to contribute significantly to the abnormally long PTT. Additionally, procoagulant titers of HF and plasma prekallikrein were relatively lower than the concentration of these factors determined immunologically. The mechanisms underlying this phenomenon are not known.
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PMID:Studies on some coagulation factors (Hageman factor, plasma prekallikrein, and high molecular weight kininogen) in the normal newborn. 743 82

Recently we have described a normal plasma activity that modulates contact activation by inhibiting adsorption of factor XI to activating surfaces. Here we report the first identified case in which a patient has abnormal clotting tests due to an excess of a similar activity. The patient's plasma had a prolonged partial thromboplastin time and low apparent factor XI assay. His plasma prolonged the partial thromboplastin time of normal plasma and partially neutralized normal factor XI activity in vivo and in vitro. Analysis in dilute plasma revealed normal amounts of factor XI activity and antigen. Factor XI adsorption from plasma to activating surfaces was tested by adding a small amount of 125I-labeled purified factor XI to plasma, exposing the mixture to a glass tube or kaolin, and determining the amount of factor XI adsorbed to the surface. Whereas normal plasma and plasmas deficient in factor XII, factor XI, or Fletcher factor yielded about 4% adsorption to glass, factor XI adsorption from patient's plasma was less than 1%, indicating the presence of an adsorption inhibitor. This inhibitor did not affect factor XI activation or the activity of preformed factor XIa. It was not adsorbed by AI(OH)3 and was present in serum and the macroglobulin peak on gel filtration of the plasma through Sephadex G-200. The patient's history does not allow a definitive conclusion as to whether this inhibitor was associated with abnormal bleeding.
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PMID:Pseudo-factor-XI deficiency: effect of an inhibitor of factor XI adsorption to surface. 745 31


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