title: Isolation and characterization of bovine factor XII (Hageman factor).
abstract: Factor XII was purified approximately 14 000-fold from bovine plasma by ammonium sulfate fractionation followed by heparin-agarose, DEAE-Sephadex, CM-cellulose, arginine-agarose, and benzamidine-agarose column chromatography. By this method, about 15 mg of protein was purified from 15 L of plasma with an overall yield of 18%. The purified protein was homogeneous as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino-terminal analysis. Bovine factor XII is a glycoprotein with a mol wt of 74 000 as determined by sedimentation equilibrium centrifugation. It contains 13.5% carbohydrate including 3.4% hexose, 4.7% N-acetylhexosamine, and 5.4% N-acetylneuraminic acid. Factor XII is a single polypeptide chain with an NH2-terminal sequence of Thr-Pro-Pro-Trp-Lys-Gly-Pro-?-Lys-His. This sequence is homologous to the reactive-site regions of a number of protease inhibitors. The amino acid sequence of a carboxyl-terminal fragments prepared by cyanogen bromide digestion was found to be Leu-Cys-Ala-Gly-Phe-Leu-Glu-Gly-Gly-Thr-Asp-Ala-Cys-Gln-Gly-Asp-SER-Gly-Gly-Pro-Leu-Val-Cys-Glu-Asp-Glu. This sequence is homologous with the active site of a number of plasma serine proteases including thrombin, factor IXa, factor Xa, and plasmin. These data indicate that bovine factor XII is a precursor to a serine enzyme with an inhibitor sequence and a catalytic site located in the same single polypeptide chain.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001665:Binding Sites; D002241:Carbohydrates / Q000032:analysis; D002417:Cattle; D002846:Chromatography, Affinity; D003488:Cyanogen Bromide; D005164:Factor IX; D005170:Factor X; D005174:Factor XII / Q000302:isolation & purification; D006493:Heparin; D008970:Molecular Weight; D010446:Peptide Fragments / Q000032:analysis; D013917:Thrombin
chemical_list: D000596:Amino Acids; D002241:Carbohydrates; D010446:Peptide Fragments; D005164:Factor IX; D005170:Factor X; D005174:Factor XII; D006493:Heparin; D013917:Thrombin; D003488:Cyanogen Bromide