Summary
Semipurified preparations of prothrombin were found to migrate slightly faster than
albumin when studied by continuous flow electrophoresis. In contrast, similar studies
with plasma, and serum enriched with prothrombin showed substantially slower migration
rates for prothrombin. Albumin was shown to be one of the plasma constituents responsible
for this change in prothrombin mobility. The broad range of prothrombin mobilities
found in plasma is ascribed to multiple interactions between prothrombin and the plasma
proteins, and not to the existence of isozymes of prothrombin.