Purification and characterization of human factor II

Human plasma Factor II has been purified approximately 800-fold by a combination of barium citrate adsorption, ion-exchange chromatography and preparative polyacrylamide gel electrophoresis. The procedure is relatively simple and results in excellent yields of purified Factor II essentially free of Factor X activity. The purified factor behaved as a single component by analytical polyacrylamide gel disc electrophoresis at pH 8.9. No Factor V, VII or IX activity was detected in the purified Factor II. Its molecular weight was 7200±3000 as determined by analytical ultracentrifugation, electrophoresis in the presence of sodium dodecyl sulfate and gel filtration on Bio-Gel P-200. An apparent molecular weight of 90 000–100 000 was observed on calibrated columns of Sephadex G-100, G-150, and G-200. The specific activity of human factor II was approximately 1300 N.I.H. units/mg as determined by the two-stage assay and 7 Ortho units/mg by the one stage assay. The purified protein contained by weight 2.8% neutral hexose, 2.3% sialic acids and 3.1% hexosamines.