Prothrombase—Its preparation and properties

Abstract

An attempt to reconcile the various hypotheses which have been advanced to account for the phenomena observed in the coagulation of blood necessitated the isolation from blood of those substances which are primarily involved in the coagulation process. In this paper the preparation of prothrombase from oxalated mammalian blood is described and the conditions under which it is converted into thrombase—the enzyme which converts fibrinogen into fibrin—are considered. In 1909 I described a method by which a solution of prothrombase may be obtained from bird's blood. Noncoagulable plasma is obtained from a fasting anæsthetised cockerel in the way described by Delezenne (1897). This plasma is diluted with 10 volumes of distilled water and brought to the isoelectric point for globulin by the cautions addition of acetic acid (1 per cent.). The precipitated golbulin is obtained as a compact mass by spinning the diluted plasma in a high-speed centrifuge. It is suspended in a volume of water equal to that of the original plasma and dissolved by the addition NaCl to the extent of 0·7 per cent. This solution contains prothrombase associated with fibrinogen. The addition to it of a little tissue extract (thrombokinase), and CaCl₂ to the extent 0·05 per cent. causes, within a few minutes, the formation of a solid coagulum of fibrin. The residual fluid, obtained after the removal of the fibrin, contains a large quantity of thrombase. If however, a small quantity of thrombase be added to the original fibrinogen-prothrombase solution coagulation takes place within a few seconds and the residual fluid, after removal of the fibrin, contains a large quantity of prothombase. The properties of avian prothrombase contained in such a solution were described. No attempt was made to isolate the prothrombase owing to the difficulty of obtaining stable noncoagulable birds' in large quantities.