Variability of the anticoagulant fraction of incubated fibrinogen

Abstract

The spontaneous breakdown of human fibrinogen or the lysis of Laki's fibrinogen by purified human fibrinolysin and streptokinase involves at least two different reactions. Clottability by thrombin and precipitability at 25% ammonium sulfate saturation are gradually lost but although clottability disappears completely at a fairly early stage, precipitability is still retained by 4–12% of the original protein even during advanced stages. Both the amount and the antithrombic activity of the anticoagulant fraction of incubated fibrinogen (AFIF) produced vary throughout fibrinogenolysis. The changing quality of AFIF is further evidenced by changes in the electrophoretic patterns which indicate variations in concentration, mobility, and number of components. Strip electrophoresis of fractions isolated by continuous-flow paper electrophoresis showed the presence of two components in the largest fraction but only of a single one of different mobility in a second, smaller fraction. The last finding makes it unlikely that the antithrombic effect exerted by the latter fraction could be due to contamination by components of the former.