Effects of Clotting on the Label in Iodinated Fibrinogen in Different Species

Abstract

Summary 1. The behaviour of the iodine label during coagulation was investigated in 8 species using 125I-fibrinogen. 2. Guinea pig, human, monkey, ox and rabbit fibrinogen preserved the label quantitatively when converted into fibrin, but goat and sheep fibrinogen lost 5.6% and canine fibrinogen lost 11.1 % of its radioactivity. 3. Using a constant iodination technique, the fraction of radioactivity released during clotting proved to be fairly reproducible. The origin and quantity of thrombin used had no influence on the results. 4. The released activity was tentatively identified in the clot liquor of sheep as 125I-fibrinopeptide B. Based on this observation, a theory is presented which satisfactorily explains the experimental findings by the variations in the occurrence of non-esterified tyrosine residues in the fibrinopeptides of different species.