Temporary Defect of Coagulation Produced in Vitro by Zymin (Dried Yeast)

¹ From the Palo Alto Hospital Research Foundation, Palo Alto, California

Treatment of plasma with zymin (acetone dehydrated yeast) causes a marked prolongation of the prothrombin time. The labile prothrombin conversion factor is not significantly affected. There is a decrease in activity of the stable prothrombin conversion factor of much smaller magnitude than the change in the prothrombin time. Mixing with an equal volume of zymin plasma does not significantly prolong the prothrombin time of normal plasma. The coagulability of zymin plasma is spontaneously restored on standing. This restoration is greatly accelerated by adsorbed oxalated bovine or canine plasma or serum, or an extract of platelets. It is suggested that the zymin effect is due to the binding of an inhibitor to the stable prothrombin conversion factor and, further, that this inhibitor may be regarded as a model of inhibitors occurring in nature.