The Preparation and Some Properties of Fibrinogen Precipitated from Human Plasma by Glycine.∗

Summary A method was described for the preparation of fibrinogen with 98% thrombin clottable protein before, and 94% clottable protein after lyophilization. The fibrinogen was precipitated from citrated prothrombinfree plasma with glycine at 0.78 saturation. pH 6.1–6.3, 20°C and purified by reprecipitation with glycine. The biological trace contaminants were plasminogen, fibrin stabilizing factor and antihemophilic globulin; prothrombin and plasmin were not found. Although fibrinogen prepared by the glycine precipitation method was very pure by the criterion of clottability and its properties were similar to those of other fibrinogen preparations, moving boundary electrophoresis and ultracentrifugation nevertheless disclosed two components in different proportions. When fibrinogen was prepared by fully saturating plasma with glycine, a beta globulin, presumably cold insoluble globulin, was a major contaminant. The precipitation of fibrinogen from plasma between 0.75 and 2.0 m glycine followed the logarithmic solubility relationship of Cohn; the salting-out constant (Ks) was 0.68.