The half-life of plasmic degradation products of human fibrinogen in rabbits.

Human fibrinogen and purified plasmic degradation fragments X (stages 1 and 2), D and E were labelled with 125-I using the lactoperoxidase method. The chromatographic, electrophoretic and immunologic properties of the labelled proteins were found to be similar to those of non-labelled fragments. All the degradation products diffused rapidly (T 1/2 0.27-0.75 hours) from the intravascular space of rabbits, as compared with fibrinogen (4.26 hours). In addition, the metabolic half-life was found to be 49.3 hours for fibrinogen, as compared with only 5.6, 6.1, 2.3 and 1.4 for fragments X (stage 1), X (stage 2), D and E, respectively. The metabolic half-life roughly reflects the molecular size of the degradation products.