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)

Protein C, a potent anticoagulant, has been detected in large amounts in some prothrombin complex concentrates (PCC). We extended these findings to eight PCC commercially available in West Germany detecting 0.82 to 1.92 plasma equivalent units of protein C antigen (PC:Ag) per unit factor IX. Infusion of PCC in four patients on stable oral anticoagulation resulted in a recovery of 58.6 +/- 10.9%. Estimated from the decrease in plasma levels of PC:Ag half life was 7.9 +/- 0.6 h.
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PMID:Protein C antigen in prothrombin complex concentrates: content, recovery and half life. 384 59

A staphylocoagulase-binding region in human prothrombin was studied by utilizing several fragments prepared from prothrombin by limited proteolysis. Bovine prothrombin, prethrombin 1, prethrombin 2, and human diisopropylphosphorylated alpha-thrombin strongly inhibited formation of the complex ("staphylothrombin") between human prothrombin and staphylocoagulase, but bovine prothrombin fragment 1 and fragment 2 had no effect on the complex formation, indicating that the binding region of human prothrombin for staphylocoagulase is located in the prethrombin 2 molecule. To identify further the staphylocoagulase-binding region, human alpha-thrombin was cleaved into the NH2-terminal large fragment (Mr = 26,000) and the COOH-terminal fragment (Mr = 16,000) by porcine pancreatic elastase. Of these fragments, the COOH-terminal fragment, which includes Asn-200 to the COOH-terminal end of the alpha-thrombin molecule, partially inhibited the complex formation between staphylocoagulase and human prothrombin. In contrast, the NH2-terminal large fragment did not show any inhibitory effect on the staphylothrombin formation. These results suggest that the staphylocoagulase interacts with human prothrombin through the COOH-terminal region of alpha-thrombin B chain. Other plasma proteins, factor X, factor IX, protein C, protein S, protein Z, all of which are structurally similar to prothrombin, did not inhibit the staphylothrombin formation at all, indicating that a specific interaction site with staphylocoagulase is contained only in the prothrombin molecule.
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PMID:Staphylocoagulase-binding region in human prothrombin. 384 93

The cellular site of synthesis of factor VIII (FVIII:C; anti-haemophilic factor) has long been sought. Previous studies suggested the liver as a major site of synthesis, but extrahepatic sources such as spleen and lung have been implicated. Using an immunoradiometric assay (IRMA), we recently localized factor VIII antigen (FVIII:Ag, formerly FVIII:CAg), to whole perfused guinea pig liver and spleen, and to isolated hepatocytes, with lesser or trace amounts in other tissues. Using an immunohistological technique, Stel et al. detected FVIII:Ag in normal human liver sinusoidal endothelial cells, while Exner et al. detected FVIII:Ag by IRMA in extracts of human lymph nodes, lung, liver and spleen. The localization of antigen in tissues does not, however, distinguish sites of factor VIII synthesis from those of storage, and such experiments are subject to misinterpretation due to entrapment of plasma factor VIII in tissues. The recent cloning of the human factor VIII gene provides hybridization probes for the detection of factor VIII messenger RNA in cells, thus directly determining sites of synthesis. During complementary DNA cloning, we detected factor VIII mRNA in liver, and it has been localized by others in liver and placenta and in liver and kidney. In the present study, we detected factor VIII mRNA in isolated human hepatocytes, in spleen and in numerous tissues including lymph nodes and kidney, but not in white blood cells or cultured endothelial cells. We also found that the factor VIII, factor VII, factor IX and protein C antigens in liver are predominantly localized in hepatocytes, while very little von Willebrand factor antigen (vWF:Ag, formerly FVIIIR Ag) is detectable in this organ.
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PMID:Distribution of factor VIII mRNA and antigen in human liver and other tissues. 393 85

A DEAE-Sephadex column chromatography step utilized to purify human Factor VII consistently yields a protein peak between the factor VII activity peak and prothrombin, factor X and factor IX activity peak (S.P. Bajaj, S.I. Rapaport, and S.F. Brown: J. Biol. Chem. 251, 253-259, 1981). We now report that this protein peak contains protein C and protein S. Preparative disc polyacrylamide gel electrophoresis of the proteins in this peak permitted a complete separation of protein C from protein S. Protein C at this step usually contained approximately 5-10% of Factor X, which could be removed by a goat anti-human Factor X antibody column. For a typical preparation, starting with 10L of plasma, the yield of Protein C was 5 mg and of protein S was 4 mg. Both proteins revealed apparent homogeneity in sodium dodecyl sulfate gel electrophoretic system. beta-Protein C and beta-protein S were not observed in our preparations starting with plasma collected directly into citrate anticoagulant containing benzamidine and soybean trypsin inhibitor, suggesting that these beta forms of protein C and protein S, isolated by other investigators, are slightly degraded forms of the native proteins. Antisera generated to these proteins were monospecific and could be used to monitor column fractions during purification. When examined by immunoelectrophoresis, the electrophoretic mobility of protein S in plasma was slower than that of isolated protein S. When exposed to plasmin, protein C was activated slightly and then rapidly degraded.
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PMID:A procedure for isolation of human protein C and protein S as by-products of the purification of factors VII, IX, X and prothrombin. 622 44

Bovine coagulation factors IX and X bind to independent sites on bovine aortic endothelial cells. Binding studies with cells maintained serum-free showed that there are at least two classes of binding sites for factor IX and factor X with a dissociation constant of 4.9 x 10(-9) M and 2.1 x 10(-8) M for the respective high affinity sites. Ca+2 was required for specific binding and was reversed by addition of EDTA or EGTA. Competition experiments showed that factor IX and factor IXa bind to the same sites, which are different from the factor X binding sites. Neither binding of factor IX or factor X is inhibited by addition of prothrombin or protein C. Indirect immunofluorescence of factor IX indicated that binding was diffuse on the cell surface.
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PMID:Binding of coagulation factors IX and X to the endothelial cell surface. 640 75

We have examined the calcium-binding properties and metal ion-dependent conformational changes of proteolytically modified derivatives of factor IX that lack gamma-carboxyglutamic acid (Gla) residues. Equilibrium dialysis experiments demonstrated that a Gla-domainless factor IX species retained a single high affinity calcium ion-binding site (Kd = 85 +/- 5 microM). Ca2+ binding to this site was accompanied by a decrease in intrinsic fluorescence emission intensity (Kd = 63 +/- 15 microM). These spectral changes were reversed upon the addition of EDTA. Titration with Sr2+ resulted in little change in fluorescence intensity below 1 mM, while titration with Tb3+ caused fluorescence changes similar to those observed with Ca2+. Tb3+ and Ca2+ appear to bind to the same site because tryptophan-dependent terbium emission was reduced by the addition of Ca2+. Similar results were obtained with a Gla-domainless factor IX species lacking the activation peptide. Gla domain-containing factor IX species exhibited fluorescence changes similar to those of the Gla-domainless proteins at low Ca2+, but an additional structural transition was found at higher Ca2+ concentrations (apparent Kd greater than 0.8 mM). Thus, the conformations of factor IX proteins are nucleated and/or stabilized by calcium binding to a high affinity site which does not contain Gla residues. The binding of Ca2+ to lower affinity Gla domain-dependent metal ion-binding sites elicits an additional conformational change. The strong similarities between these results and those obtained with protein C (Johnson, A. E., Esmon, N. L., Laue, T. M. & Esmon, C. T. (1983) J. Biol. Chem. 258, 5554-5560), coupled with the remarkable sequence homologies of the vitamin K-dependent proteins, suggest that the high affinity Gla-independent Ca2+-binding site may be a common feature of vitamin K-dependent proteins.
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PMID:Derivatives of blood coagulation factor IX contain a high affinity Ca2+-binding site that lacks gamma-carboxyglutamic acid. 642 96

Protein C is a precursor to a serine protease that is present in mammalian plasma. In its activated form, it readily inactivates factor Va and factor VIIIa, two proteins that participate as cofactors in the blood coagulation cascade. In the present studies, a lambda gt11 library containing cDNA inserts prepared from human liver mRNA has been screened with an antibody to human protein C. Seven positive clones were isolated from 2 X 10(6) phage and were plaque-purified. The cDNA inserts of two of these phage were sequenced and shown to code for human protein C. Each cDNA insert coded for a portion of the light chain of the molecule, a connecting region, the heavy chain, a stop codon, a 3'-noncoding region, and a poly(A) tail. The length of the noncoding sequence on the 3' end differed in the two clones, but each contained a processing or polyadenylylation signal followed by a poly(A) tail. The amino acid sequence as determined from the cDNA indicates that protein C is synthesized as a single-chain polypeptide containing the light chain and the heavy chain connected by a dipeptide of Lys-Arg. The single-chain molecule is then converted to the light and heavy chains by cleavage of two or more internal peptide bonds. In plasma, the heavy and light chains of protein C are linked together by a disulfide bond. The amino acid sequence of human protein C shows a high degree of homology with that of the bovine molecule. The DNA sequence coding for the catalytic region near the active site serine in human protein C also showed a high degree of DNA and amino acid sequence identity with prothrombin, factor IX, and factor X, three of the other vitamin K-dependent serine proteases that are present in plasma.
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PMID:Characterization of a cDNA coding for human protein C. 658 23

A method for the quantitation of beta-hydroxyaspartic acid in proteins is described. After hydrolysis in 6 M HCl, the beta-hydroxyaspartic acid released is quantitated on an automatic amino acid analyzer employing a pH 2.0 eluting buffer and postcolumn reaction with o-phthalaldehyde for detection. The sensitivity is about 0.01 nmol. Among vitamin K-dependent proteins, factor IX, factor X, protein C, and protein Z each contain about one residue of beta-hydroxyaspartic acid whereas protein S contains two or three residues. Prothrombin lacks beta-hydroxyaspartic acid as do a number of non-vitamin K-dependent proteins also analyzed.
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PMID:Beta-hydroxyaspartic acid in vitamin K-dependent proteins. 663 Jan 96

Previous work has shown that two vitamin K-dependent plasma zymogens, factor X and protein C, each contain one residue of erythro-beta-hydroxyaspartic acid. In the present study, prothrombin, factor VII and factor IX were subjected to amino acid analyses for beta-hydroxyaspartic acid. Factor IX and factor VII each contain one residue of erythro-beta-hydroxyaspartic acid. Edman sequence analyses revealed that this residue occurs at position 64 in human and bovine factor IX. Inasmuch as the nucleotide sequence codes for aspartic acid at this position, it appears highly likely that beta-hydroxyaspartic acid is formed in these proteins by a post-translational hydroxylation of aspartic acid. In contrast, neither human nor bovine prothrombin contain beta-hydroxyaspartic acid.
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PMID:The occurrence of beta-hydroxyaspartic acid in the vitamin K-dependent blood coagulation zymogens. 668 26

The amino acid sequence of the light chain of the vitamin K-dependent protein C from bovine plasma is reported together with the supporting data. The sequence was determined by sequenator analysis of intact light chain, which contains 155 amino acid residues, and fragments obtained by chemical and enzymatic degradation of the light chain. All 11 glutamyl residues up to position 44 are carboxylated as gamma-carboxyglutamic acid residues. This part of the molecule proved very homologous to the other vitamin K-dependent plasma proteins. The remaining part (111 residues) is homologous to the corresponding parts in factor IX and factor X but not to prothrombin.
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PMID:Amino acid sequence of the light chain of bovine protein C. 689 76


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