Russell F Doolittle, Douglas M Surgenor
Blood coagulation systems in cyclostome, elasmobranch, and teleost fish were studied and compared. The plasma of all these fish contained a fibrinogen molecule, capable of being clotted by human thrombin, and a prothrombin molecule, capable of being converted into thrombin which could hydrolyze p-tosyl l-arginine methyl ester. The prothrombin activity could be adsorbed on barium sulfate. Accurate assessment of prothrombin conversion factors is confounded by the "species specificity" of protein-protein interactions, but preliminary observations were made on both the extrinsic and intrinsic clotting schemes...
November 1962: American Journal of Physiology