Effect of prothrombin supplementation on thrombin generation. Thrombin generation during clot lysis was determined in samples consisting of normal plasma (100% prothrombin, •) or plasma supplemented with purified prothrombin to obtain a total prothrombin concentration of 150% (▴). Thrombin activity was measured by clotting assay on aliquots taken from the clot lysis mixture at the indicated intervals. The dotted line refers to normal plasma in which coagulation was triggered by a 10-fold higher concentration of thromboplastin. Results are the mean of 3 experiments. SDs were omitted for clarity.