Pathways to Blood Coagulation Product I Formation

The basic reagent used was an eluate obtained from barium sulfate usedto adsorb various sera. When this eluate was prepared from normal rabbitserum, it responded to treatment with coagulants from adsorbed plasma,with Stypven, or with 25 per cent sodium citrate to give products withsimilar if not identical properties. With each preparation a stable complexformed with cephalin which withstood washing, was relatively heat-stable,was inactivated by adsorbed serum, and which required factor V for optimalprothrombin conversion. In eluates prepared from human serum, normalactivation occurred in the absence of factor IX, but was defective in theabsence of factor X. A preparation of factor X purified by DEAE cellulosechromatography was activated by 25 per cent sodium citrate. It is suggestedthat product I, the product of Stypven activation, and autoprothrombin Crepresent similar or identical reagents; it is further suggested that factor Xis their common precursor.

Submitted on November 7, 1962 Accepted on January 23, 1963