Recombinant mouse prothrombins and activated products. Recombinant aaII and rrII were proteolytically activated and the products aaMZa, aaMZdesF1a, and thrombin were purified and analyzed by gel electrophoresis. The gel was stained with Coomassie blue, and the positions of molecular weight standards (kDa) are indicated. Purified human plasma prothrombin was included for comparison. The major product of aaII activation with E carinatus venom is aaMZa (lane 2), which is converted slowly by autoproteolysis to aaMZdesF1a (lane 5). Activation of aaII to aaMZa (lane 2) was quantitative as shown by disappearance of the aaMZa band upon electrophoresis under reducing conditions.