On the fibrin forming and geloplastic activities of electrophorosed bovine thrombin preparations

Abstract

Bovine thrombin preparations from two different lots (Parke-Davis) were separated into 30 sections by acrylamide gel electrophoresis. The eluates of these sections were pooled into 8 fractions and their protein contents were determined. The eluates of the 8 fractions were then added to fibrinogen systems with or without the addition of the non-electrophorosed thrombin preparation and determinations of the fibrin time and gelation time were made. This simple method permits the differentiation between fibrin polymerization and gelation. Our findings suggest that the thrombin preparation contains different components besides the thrombin enzyme and that the geloplastic action can be readily recognized from the fibrin forming action of the thrombin preparation. By “fibrin formation” is meant partial proteolysis of fibrinogen with subsequent formation of fibrin fibrils. The thrombin preparation contained also components which have anticoagulant activity both as antithrombin and as antigeloplastin. The thrombin preparation therefore appears to be a composite of substances with different specific activities. In the discussion it was pointed out that what hitherto has been ascribed as enzymatic action of thrombin should not be confused with other activities residing in the same thrombin preparation. Thus the choice of gelation as an endpoint for thrombin assays measures actually the activity of the geloplastic component. Moreover, the role ascribed to thrombin in the activation of factor XIII and the source of factor XIII by the use of plasma concern also the geloplastic component of the thrombin preparation. The difference between fibrin formation formation and gelation is emphasized on theoretical grounds as two different processes of fibrin coagulation, followed by the process of cross-linking due to factor XIII. Our findings, which are not merely of theoretical interest, have wide applications in the treatment and prevention of certain thrombotic conditions, affecting especially the large blood vessels where the gelation of fibrin is of particular significance.