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)

Rates of hydrolysis of the newly developed peptide chromogenic substrates S-2160 (N-Bz-Phe-Val-Arg-pNA, HCl), S-2238 (H-D-Phe-Pip-Arg-pNA, 2HCl), S-2222 (N-Bz-Ile-Glu-Gly-Arg-pNA, HCl), and S-2251 (H-D-Val-Leu-Lys-pNA, 2HCl) from AB Kabi Peptide Research and Chromozym TH (Z-Gly-Pro-Arg-pNA, HCl) from Pentapharm Limited were tested against highly purified preparations of human plasmin, bovine trypsin, human alpha thrombin, and bovine factor Xa. S-2160, S-2238, and Chromozym TH are sensitive to thrombin, Chromozym TH and S-2238 exhibiting a substantially greater sensitivity than S-2160. All 3 substrates are insensitive to factor Xa but hydrolyzed to varying degrees by plasmin and trypsin. In contrast, S-2222 is sensitive to Xa and insensitive to thrombin. S-2251 is relatively plasmin-specific, being resistant to the clotting enzymes thrombin and Xa. S-2251 exhibits even greater sensitivity to the SK-plasmin complex than to plasmin. In addition, the substrate Chromozym PK (N-Bz-Pro-Phe-Arg-pNA, HCl) was evaluated and found to be relatively specific for plasma kallikrein. Assays for antithrombin III and heparin using S-2222 as the substrate and factor Xa as the enzyme, plasma plasminogen and plasmin inhibitors using S-2251 as the substrate, and plasma prekallikrein and kallikrein inhibitors using Chromozym PK as the substrate have been developed. Synthetic peptides mimicking amino acid sequences adjacent to proteolytic activation cleavage of plasma serine protease precursors appear to be sensitive and relatively specific tools applicable to kinetical and clinical studies of these enzymes and their inhibitors.
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PMID:Serine protease specificity for peptide chromogenic substrates. 14 72

A blood coagulation deficiency was found at the contact phase in identical Japanese female twins. Of the four possible factors involved, Factor XI or XII can be ruled out according to cross-correction studies. The problem factor was probably not Fletcher factor, because the abnormal partial thromboplastin time was not significantly shortened by increasing the incubation period of plasma with kaolin. The deficiency is most likely due to the lack of Fitzgerald factor.
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PMID:Coagulation factor deficiency apparently related to the Fitzgerald trait: the first cases in Japan. 14 37

Rates of hydrolysis of the newly developed peptide chromogenic substrates S-2160, S-2238, S-2222 and S-2251 and Chromozym TH were tested against highly purified preparations of human plasmin, bovine trypsin, human alpha-thrombin, and bovine factor Xa. S-2160, S-2238, and chromozym TH are sensitive to thrombin, Chromozym TH and S-2238 exhibiting a substantially greater sensitivity than S-2160. All three substrates are insensitive to factor Xa but hydrolyzed to varying degrees by plasmin and trypsin. In contrast, S-2222 is sensitive to factor Xa and insensitive to thrombin. S-2251 is relatively plasmin-specific. In addition, the substrate Chromozym PK was evaluated and found to be relatively specific for plasma kallikrein. Clinically useful assays for antithrombin III and heparin using S-2222 as the substrate and factor Xa as the enzyme, plasma plasminogen and plasmin inhibitors using S-2251 as the substrate, and plasma prekallikrein and kallikrein inhibitors using Chromozym PK as the substrate have been developed.
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PMID:Sensitivity and specificity of plasma serine protease chromogenic substrates. 14 51

The prolonged activated partial thromboplastin times observed with Fletcher factor (prekallikrein)-deficient plasmas become nearly normal after the plasma is incubated with contact surfaces or with an activator. Those shorter times may lead to relatively flat reference curves for Fletcher factor assays under certain conditions. The authors examine in detail the effect of incubation time upon the sensitivity of Fletcher factor assays. Four different surface activators were used in the tests to determine the optimal activation for each type. An incubation time of 1 min produced maximal sensitivity with each surface activator tested. All reagents remained stable for at least an hour at 37.5 C.
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PMID:Laboratory suggestions: Improving the sensitivity of the Fletcher factor assay. 45 74

Studies of plasmas from individuals with Hageman trait (factor XII deficiency), plasma thromboplastin antecedent (PTA, factor XI) deficiency, Fletcher trait (plasma prekallikrein deficiency) and Fitzgerald trait (high molecular weight-kininogen deficiency) have revealed the importance of these proteins in blood coagulation. The interactions among them, however, are not fully elucidated. We have studied these reactions by two different approaches. (1) In a purified system, high molecular weight kininogen was absolutely required for activation of PTA by HF and ellagic acid (EA). The yield of activated PTA was proportional to the amount of HF, HMW-K, and PTA in the mixtures, suggesting that these three proteins may form a complex in the presence of EA. (2) In experiments with whole plasma, we took advantage of the adsorption of EA to Sephadex gels. When normal plasma or plasma deficient in HF, PK, HMW-K or PTA was exposed to Sephadex-EA and was separated by centrifugation, each supernatant plasma except that deficient in HF shortened the prolonged partial thromboplastin time (PTT) of HF-deficient plasma. Plasma simultaneously depleted of HMW-K, PK and PTA also shortened the PTT of HF-deficient plasma and of plasma depleted of HF and PK, but had virtually no procoagulant effect upon the PTT of plasma depleted of HF and MHW-K. Thus, exposure of HF in plasma to Sephadex-EA appeared to generate a clot-promoting form of HF in the absence of other clotting factors, but its expression required the presence of HMW-K.
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PMID:Interactions among Hageman factor (HG, Factor XII), plasma thromboplastin antecedent (PTA, Factor XI), plasma prekallikrein (PK, Fletcher factor) and high molecular weight kininogen (HMW-K, Fitzgerald factor) in blood coagulation. 51 54

Evidence of developmental evolution of coagulation can be seen when the studies of 10 thriving extremely premature (EPT) infants are compared to normal full-term (FT) infants. The prothrombin time, partial thromboplastin time, and thrombin time all became shorter with increasing gestational age. Fibrinogen levels and platelet counts appear to be comparable to term infant and adult levels. Fibrin degradation products (FDP) of 10 micrograms/ml or less were found in the thriving EPT infants. When compared to healthy full-term infants, there is a definite gestational dependency of anti-thrombin III levels. Factors II and VII appear to be related to intrauterine maturation after the age of viability (24 wk), but factor VII-X complex does not. The contact factors XI, XII, high molecular weight kininogen (Fitzgerald factor), and prekallikrein (Fletcher factor) are all markedly decreased in thriving EPT infants. The mean factor V level is lower than that found in FT infants. This study confirms a gestational age dependency of factor VIII activity. The ratio of factor VIII antigen to factor VIII clotting activity is increased (2.8 vs 1.01 in FT and adults). Thriving small for gestational age (SGA) infants had coagulation studies which were not statistically different from those of thriving EPT infants. The coagulation changes which occurred in severely ill EPT were mainly in the factors which decrease during intravascular coagulation (factors I, V, and VIII). The present study suggests that because of the high antigen to activity ratio seen in thriving EPT infants, a dysfunctional or fetal factor VIII may have been produced. However, the further elevation of this ratio in the severely ill EPT infants is in keeping with a pathologic proteolysis or increased endothelial release of factor VIII antigen.
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PMID:Coagulation studies in extremely premature infants. 52 93

Blood clotting and fibrinolytic systems were studied in the plasma of a sei whale (Balaenoptera borealis). The sei whale belongs to the suborder baleen whales of the order Cetacea. Whale plasma had a greatly prolonged kaolin-activated partial thromboplastin time and was deficient in Hageman factor (factor XII), Fletcher factor (a plasma prekallikrein), and PTA (factor XI). All other clotting factor activities were present in amounts comparable to that of normal human plasma. Whale plasminogen was activated by human urokinase, but not by streptokinase. Whale plasma contained inhibitory activities against thrombin, activated Stuart factor, activated PTA, activated Fletcher factor, and plasmin.
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PMID:Studies on the blood clotting and fibrinolytic system in the plasma from a sei (baleen) whale. 96 76

This paper reports an asymptomatic coagulation defect responsible for an abnormality at the contact phase of blood coagulation in vitro, distinct from Hageman factor and Fletcher factor deficiencies. Coagulation studies in a 50-yr-old French woman without bleeding tendency revealed the following results: whole-blood clotting time in glass tubes and activated partial thromboplastin time with kaolin and ellagic acid were greatly prolonged; one-stage prothrombin was normal; no circulating anticoagulant was detected, and the infusion of normal plasma corrected the coagulation defect with an estimated half-life of 6.5 days; the levels of factor VIII, IX, XI, and XII were normal; mutual correction was obtained with a Fletcher factor-deficient plasma; the level of whole complement was normal. Studies of the contact phase of blood coagulation and contact-induced fibrinolysis showed the same abnormalities as in Hageman factor- and Fletcher-deficient plasmas. These results indicate that the patient's plasma is deficient in a previously undescribed coagulation factor, which participates in the initial stage of the blood coagulation process in vitro. Family studies revealed consanguinity in the propositus' parents. The assay of this newly described factor in the propositus' children revealed a partial defect, compatible with a heterozygous state, in three of the four tested children. This indicates a recessive inheritance of this new blood coagulation defect.
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PMID:A hitherto undescribed plasma factor acting at the contact phase of blood coagulation (Flaujeac factor): case report and coagulation studies. 117 9

The contact phase of intrinsic clotting involves Factor XI, Factor XII, Fletcher factor, and a fourth activity that we call contact activation cofactor (CAC). All four of these activities are reduced or absent in Dicalite-adsorbed plasma. A modified activated partial thromboplastin time assay for CAC has been defined by using a substrate of Dicalite-adsorbed plasma combined with partially purified sources of Factors XI and XII, and Fletcher factor. The following properties of CAC in plasma have been determined by using the assay: it is stable up to 60 min at 56 degrees C; gradually loses activity at 80 degrees C; is stable between pH 6 and 9; is precipitated by ammonium sulfate between 40% and 50% saturation; is slightly adsorbed by A1(OH)3; and is eluted from DEAE-cellulose after the major protein peaks. A purification procedure has been devised that separates CAC from other known clotting factors. Isolated CAC was less stable than CAC in plasma, but in the presence of dilute human serum albumin it retained full activity for 80 min at 56 degrees C. On gel filtration CAC had an apparent mol wt of 220,000 daltons. These properties are consistent with those described for Fitzgerald factor, which further supports the conclusion that CAC and Fitzgerald factor represent the same activity. Isolated CAC promoted the generation of activated Factor XI (XIa) in a mixture containing purified Factor XI, Factor XII, and kaolin. The amount of Factor XIa generated was proportional to the amount of added CAC. No time-consuming reaction between Factor XI or Factor XII and CAC could be demonstrated.
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PMID:Partial purification and characterization of contact activation cofactor. 118 36

An asymptomatic woman (Ms. Williams) was found to have a severe abnormality in the surface-activated intrinsic coagulation, fibrinolytic, and kinin-generating pathways. Assays for known coagulation factors were nromal while Fletcher factor (pre-kallikrein) was 45%, insufficient to account for the observed markedly prolonged partial thromboplastin time. Plasminogen proactivator was present at 20% of normal levels and addition of highly purified plasminogen proactivator containing 10% plasminogen activator partially corrected the coagulation and fibrinolytic abnormalities but not the kinin-generating defect. This effect was due to its plasminogen activator content. In addition, Williams trait plasma failed to convert prekallilrein to lakkilrein or release kinin upon incubation with kaolin. Kininogen antigen was undetectable. When normal plasma was fractionated to identify the factor that corrects all the abnormalities in Williams trait plasma, the Williams factor was identified as a form of kininogen by its behavior on ion exchange chromatography, gel filtration, disc gel electrophoresis, and elution from an anti-low molecular weight kininogen immunoadsorbent. High molecular weight kininogen as well as a subfraction of low molecular weight kininogen, possessed this corrective activity while the bulk of low molecular weight kininogen functioned only as a kallikrein substrate. Kininogen therefore is a critical factor required for the functioning of Hageman factor-dependent coagulation and fibrinolysis and for the activation of prekallikrein.
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PMID:Williams trait. Human kininogen deficiency with diminished levels of plasminogen proactivator and prekallikrein associated with abnormalities of the Hageman factor-dependent pathways. 120 89


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