Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.69 (APC)
 16,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The amino acid sequence of the light chain of bovine protein C was determined by sequenator analysis of the carboxymethylated light chain and fragments obtained by cyanogen bromide treatment, tryptic digestion after blocking of lysine residues, and cleavage with 2-(2-nitrophenylsulfenyl)-3-methyl-3-bromoindolenine (BNPS-skatole). The sequence was (in the standard one-letter code) A-N-S-F-L-X-X-L-R-P-G-N-V-X-R-X-C-S-X-X-V-C-X-F-X-X-A-R-X-I-F-Q-N-T-X-D-T-M-A-F-W-S-K-Y-S-D-G-D-Q-C-E-D-R-P-S-G-S-P-C-D-L-P-C-C-G-R-G-K-C-I-H-G-L-G-G-F-R-C-D-C-A-E-G-W-E-G-R-F-C-L-H-E-V-R-F-S-N-C-S-A-E-B-G-G-C-A-H-Y-C-M-E-E-E-G-R-R-H-C-S-C-A-P-G-Y-R-L-E-D-D-H-Q-L-C-V-S-K-V-T-F-P-C-G-R-L-G-K-R-M-E-K-K-R-K-T-L. The first eleven glutamic acid residues were carboxylated to gamma-carboxyglutamic acid (X). The NH2-terminal, vitamin K-dependent part showed an extensive homology to both prothrombin and factor X, whereas the rest of the chain showed a strong homology to factor X but little similarity to prothrombin.
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PMID:Bovine protein C: amino acid sequence of the light chain. 28 10

The amino acid sequence of bovine blood coagulation Factor IX (Christmas Factor) is presented and compared with the sequences of other vitamin K-dependent plasma proteins and pancreatic trypsinogen. The 416-residue sequence of Factor IX was determined largely by automated Edman degradation of two large segments, containing 181 and 235 residues, isolated after activating Factor IX with a protease from Russell's viper venom. Subfragments of the two segments were produced by enzymatic digestion and by chemical cleavage of methionyl, tryptophyl, and asparaginyl-glycyl bonds. Comparison of the amino acid sequences of Factor IX, Factor X, and Protein C demonstrates that they are homologous throughout. Their homology with prothrombin, however, is restricted to the amino-terminal region, which is rich in gamma-carboxyglutamic acid, and the carboxyl-terminal region, which represents the catalytic domain of these proteins and corresponds to that of pancreatic serine proteases.
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PMID:Comparison of amino acid sequence of bovine coagulation Factor IX (Christmas Factor) with that of other vitamin K-dependent plasma proteins. 29 16

Bovine platelets that have been activated by thrombin facilitate the conversion of prothrombin to thrombin in the presence of calcium ions and factor Xa. Activated protein C, a vitamin-K-dependent plasma protein, inhibits this platelet prothrombin-converting activity. The inhibition is time dependent and is not reversed by increasing concentrations of factor Xa. However, factor Xa is able to protect the platelet prothrombin-converting activity from inactivation by activated protein C. The activated protein C causes a parallel loss of factor Xa receptor sites and platelet prothrombin-converting activity. Activated protein C may contribute to the regulation of clotting through inactivation of the platelet prothrombin-converting activity.
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PMID:Activated protein C inhibits platelet prothrombin-converting activity. 50 37

The membrane-binding characteristics of six vitamin K dependent plasma proteins, which have homologous amino acid sequences, were compared. All of these proteins display calcium-dependent membrane binding and the identified equilibria for protein-membrane binding are qualitatively the same for all proteins. Quantitative characteristics of these protein-membrane interactions allow organization into distinct subgroups. Protein C and factor VII form a subgroup which has extemely low affinity for bilayer membranes; prothrombin, factor X, and protein S form the tightest complexes with membranes and factor IX displays intermediate affinity. In the presence of manganese (which substitutes for calcium in a cation-dependent protein transition), calcium titration of protein-membrane binding shows the same calcium dependence for all proteins except prothrombin which requires lower calcium. These protein-membrane binding characteristics agree very well with the relatedness of these proteins based on their partial amino-terminal sequences.
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PMID:Interaction of vitamin K dependent proteins with membranes. 56 56

Improved methods are described to obtain bovine prothrombin, Factor IX, Protein C, and autoprothrombin III (Factor X, Auto-III) in purified form. The prothrombin had a specific activity of 4,340 Iowa units/mg. Theoretically, a preparation of clean thrombin should have a specific activity of 8,200 U/mg, because 47.08% of the protein in prothrombin is lost when thrombin forms. Such thrombin preparations have been obtained (Arch. Biochem. Biophys. 121, 372 (1967)). The prothrombin concentration of bovine plasma is near 60 mg/liter. Protein C, first isolated by Stenflo (J. Biol. Chem. 251, 355 (1976)), was found to be the precursor of autoprothrombin II-A (Auto-II-A), discovered earlier (Thromb. Diath. Haemorrh. 5, 218 (1960)). Protein C (Factor XIV) was converted to Auto-II-A (Factor XIVa) by thrombin. Digesting purified Auto-III with purified thrombin removed a small glycopeptide from the COOH-terminal end of the heavy chain to yield Auto-IIIm. Auto-III thrombin leads to Auto-IIIm + peptide. Auto-IIIm was not converted to the active enzyme with thromboplastin, and furthermore, inhibited the activation of purified native Auto-III with thromboplastin. Auto-IIIm was also not converted to the active enzymes when the procoagulants consisted of purified Factor VIII, purified Factor IXa, platelet factor 3 and calcium ions. The "activation peptide" released by RVV-X from the NH2-terminal end of the heavy chain and the active enzyme (Auto-Cm) were purified. Auto-III was also activated with purified RVV-X. The same "actid of Auto-Cm. Purified Factor IX developed anticoagulant activity when reacted with an optimum concentration of purified thrombin. A suitable reagent for the assay of Factor IX was prepared by removing prothrombin complex from anticoagulated bovine plasma and restoring the prothrombin and Auto-III concentration with use of the respective purified proenzymes.
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PMID:Improved procedures for the purification of selected vitamin K-dependent proteins. 78 72

Conclusive evidence is presented that a recently purified (Stenflo, J. (1976) J. Biol. Chem. 251, 355-363) vitamin K-dependent protein (arbitrarily referred to as Protein C) which is not related to prothrombin, Factors IX or X is also unrelated to Factor VII. It therefore appears to be a new, previously unrecognized vitamin K-dependent protein. In contrast to prothrombin, which binds to negatively charged phospholipid only in the presence of Ca2+ ions, Protein C, like the other vitamin K-dependent proteins, is a precursor of a serine esterase, presumably a protease, but it does not seem to be necessary for blood coagulation. Although the lipid-binding properties of Protein C may suggest that it is associated with membrane structures, its biological function remains unknown.
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PMID:A new vitamin K-dependent protein. A phospholipid-binding zymogen of a serine esterase. 127 Apr 37

The extent and time course of changes in selected procoagulant and anticoagulant factors were investigated in 19 patients undergoing elective abdominal aortic surgery. The coagulation factors were measured preoperatively, and on days two, four, and six postoperatively. It was found that there were no significant changes outside the normal range in prothrombin time, partial thromboplastin time, or thrombin clotting time. However, there were large increases in the procoagulants, fibrinogen, factor VIII coagulant, factor VIIIRag/von Willebrand factor, and in alpha 1-antitrypsin. Over the same time there were marked decreases in the naturally occurring anticoagulants, protein C and antithrombin III, and in alpha 2-macroglobulin. These changes implied that the patients were "hypercoagulable" in the postoperative period. The maximum changes in the procoagulants occurred on either postoperative day two or day four. The maximum changes in the natural anticoagulants occurred on postoperative day two. There were no significant changes in factor V, factor X, alpha 2-antiplasmin, or platelet aggregability. The timing of the changes coincided with a period of high risk of perioperative myocardial infarction in this group of patients. Thus, it is possible that postoperative hypercoagulability contributes to the development of coronary artery thrombosis and myocardial infarction following abdominal aortic surgery.
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PMID:Postoperative changes in coagulant and anticoagulant factors following abdominal aortic surgery. 128 42

Antiphospholipid antibodies (APA) are a family of immunoglobulins that react with anionic phospholipids, or anionic phospholipids-protein complexes. Recent evidence would support the latter definition. Lupus anticoagulants (LA) inhibit in vitro phospholipid dependent coagulation tests [e.g., activated partial thromboplastin time (APTT), prothrombin time (PT), and dilute Russell viper venom time (dRVVT)]. This inhibition appears to be specific for reagent phospholipids. The addition of freeze-thawed platelets or activated platelets will result in correction of the LA-induced abnormality. Anticardiolipin antibodies (ACA) are related to LA but appear to be distinct. ACA are detected by solid phase assays (ELISA, RIA) and require a plasma cofactor: beta 2 Glycoprotein-I (beta 2 GPI). ACA and LA activities can be separated in individual patient plasmas by affinity chromatography. In some instances they are of differing isotypes. Preliminary evaluation of beta 2 GPI in coagulation assays suggests it may function as a cofactor for LA activity. Recent work also suggests human prothrombin may represent a necessary cofactor for in vitro LA activity. Paradoxically, patients with LA/ACA may sustain thromboembolic events involving both venous and arterial sites. The prothrombotic properties of LA/ACA have not been satisfactorily characterized. A number of proposals have been reported, including inhibition of prostacyclin (PGI2) generation by endothelial cells, decreased activity of the protein C system, impaired fibrinolysis, and inhibition of beta 2GPI. Among these various hypotheses, down regulation of the protein C system appears most plausible. Also, LA/ACA may interfere with the phospholipase A2-phospholipid substrate complex involved in the generation of arachidonic acid from membrane phospholipids.
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PMID:Antiphospholipid antibodies: proposed mechanisms of action. 128 81

To investigate the status of the protein C-protein S anticoagulant pathway in thalassemic patients, we measured protein C and protein S levels of plasma of 30 adults and 18 children with beta-thalassemia/HbE disease, beta-thalassemia major and HbE disease. Mean +/- 1 SD values of protein C, protein S and other coagulant proteins produced by the liver were as follows: protein C 50.4 +/- 17.2%; protein S 58.8 +/- 25.5%; antithrombin III 78.1 +/- 12.8%; PLG 86.4 +/- 18.4%; prothrombin 71.0 +/- 13.1%; factor VII 72.7 +/- 21.5%; and factor X 79.2 +/- 15.6%. Protein C and protein S levels of thalassemic patients were significantly lower than those of other coagulant proteins produced by the liver. Decrease in protein C level was stronger than that of proteins S. gamma-Carboxylated protein C levels of splenectomized patients were significantly lower than those of nonsplenectomized patients. Severe decrease of protein C and protein S may be responsible for occurrence of thrombosis in thalassemic patients.
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PMID:Protein C and protein S deficiency in thalassemic patients. 129 96

The variations of the main plasma inhibitors of coagulation were prospectively studied in 33 cirrhotic patients, of which 9 presented with hepatocellular carcinoma, 5 of those associated with portal vein thrombosis. The mean prothrombin index was 49 +/- 16 percent. All plasma values of inhibitors were diminished, but to varied degrees: the mean values were: protein C (PC): 33 +/- 15 percent, antithrombin III (AT III): 50 +/- 23 percent, total protein S (PST): 67 +/- 20 percent. The more severe the cirrhosis, the more decreased were the values of antithrombin II and protein C. According to Child classes A, B, and C, antithrombin III plasma values were 64 +/- 20, 50 +/- 21 and 26 +/- 11 percent and protein C values were 43 +/- 16, 32 +/- 8 and 19 +/- 9 percent, respectively. We were able to define expected plasma values of the plasma inhibitors as a function of coagulation factors during cirrhosis; AT III (percent) = 1.16 x factor II (percent) - 7.85; PC (percent) = 0.49 x AT III (percent) + 8.96; PC (percent) = 0.55 x factor II (percent) + 5.55; PST (percent) = 0.76 x factor II (percent) + 28.74. However those equations cannot be extrapolated to patients presenting with cirrhosis complicated with portal thrombosis.
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PMID:[Changes in levels of blood coagulation inhibitors in cirrhosis. Prospective study in 33 patients]. 131 44


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