Identification of proteins adsorbed from human plasma to glass bead columns: plasmin-induced degradation of adsorbed fibrinogen.

In a bead column experiment, attempts have been made to identify the proteins adsorbed from plasma onto a glass surface. Proteins adsorbed after a 3-h contact time were eluted sequentially by 1 M tris buffer and SDS. Polyacrylamide gel electrophoresis of eluted proteins showed a multiplicity of components, and not all of these could be identified. Positive identifications were made by immunodiffusion against specific antibodies, band positions on electrophoresis gels, and location of radioactivity in gels when specific radiolabeled proteins were added to plasma. Proteins found were albumin, IgG, fibrinogen, plasminogen, and fibrinogen degradation products (FDP). A major component with an apparent molecular weight of 25,000 remains unidentified. It is unrelated to albumin, IgG, fibrinogen, factor XII, or plasminogen. Adsorbed fibrinogen was less degraded when experiments were performed with plasmas deficient in either plasminogen or factor XII. It is therefore concluded that FDP are formed by activation of adsorbed plasminogen, as was found previously for purified fibrinogen containing a trace of plasminogen. At least part of this activation is potentiated by the contact activation phase of plasma coagulation, in particular activated factor XII.