No abstract

Summary. Thin layer two phase acrylamide gel electrophoresis was used for separation of fibrinogen and fibrin degradation products which were subsequently quantitated by scanning. The use of 6 m urea in the spacer gel greatly improved separation. Three main fibrinogen fragments X, Y and D and minor fragments E1, E2 and E3 were identified. During plasmin digestion of fibrinogen, Fragment X gradually decreased and Fragment D increased. The concentration of Fragment Y was rather low as would be expected of an intermediate product in the conversion of X to D. At various times of proteolysis, there was good agreement between the level of Fragment X determined by electrophoresis and the amount of protein precipitated at low concentration of protamine sulphate (PS) from the digest pretreated with thrombin. The study supports the concept of two varieties of Fragment X, one with fibrinopeptides (Xfp)—in fibrinogen degradation products (FDP)—and one devoid of fibrinopeptides (X°)—in fibrin degradation products (fdp). During electrophoresis without urea, Fragment X° undergoes extensive polymerization in the slots and gel because of its dissociation from complexes with Fragments Y and D. In the presence of urea, Fragment X° of the early fibrin digest had slower electrophoretic mobility than Fragment Xfp. The mobility of other fibrinogen fragments was not affected by thrombin.