Human Plasma Protein C

摘要: Abstract Protein C is a vitamin K-dependent protein, which exists in bovine plasma as precursor of serine protease. In this study, protein was isolated to homogeneity from human by barium citrate adsorption and elution, ammonium sulfate fractionation, DEAE-Sephadex chromatography, dextran agarose preparative polyacrylamide gel electrophoresis. Human (Mr = 62,000) contains 23% carbohydrate composed light chain 21,000) heavy 41,000) held together disulfide bond(s). The has an amino-terminal sequence Ala-Asn-Ser-Phe-Leu- the aminoterminal Asp-Pro-Glu-Asp-Gln. residues that are identical underlined. Incubation with α-thrombin at enzyme substrate weight ratio 1:50 resulted formation activated C, amidase activity. activation reaction, apparent molecular decreased 41,000 40,000 determined electrophoresis presence sodium dodecyl sulfate. No change observed process. also active-site residue evidenced its ability react radiolabeled diisopropyl fluorophosphate. markedly prolongs kaolin-cephalin clotting time plasma, but not plasma. amidolytic anticoagulant activities were completely obviated prior incubation These results indicate like counterpart, zymogen converted protease limited proteolysis attendant