Selective plasminogen binding: Cysteinyl–lysine–dextran protein interactions

The dipeptide, image-cysteine–image-lysine, when coupled to a dextran matrix demonstrates a much higher binding of Glu–plasminogen than dextran alone. Plasminogen binds to the dipeptide coupled matrix with a high affinity and binding capacity and is retained by the surface for long periods. In comparison, other proteins such as bovine serum albumin, α2-antiplasmin, tPA, fibrinogen, and plasmin are not retained by the material demonstrating that the image-cysteine–image-lysine–dextran is highly selective for Glu–plasminogen. While fibrinogen alone does not bind to the surface, fibrinogen on surfaces to which plasminogen has been pre-adsorbed does demonstrate adsorption interactions. The nature of the interactions depend on the amount of plasminogen bound. Fibrinogen in contact with high concentrations of adsorbed plasminogen causes an increase in the desorption rate of the surface bound protein; if low amounts of plasminogen are initially bound, fibrinogen exposure causes an increase in total protein adsorbed by the surface. A higher amount of protein adsorbs from a mixed plasma solution. This does not appear to inhibit the binding of plasminogen, but rather may actually facilitate more plasminogen binding than is the case of plasminogen alone. The dipeptide coupled to the dextran matrix appears to be a preferred substrate for plasminogen binding compared to free lysine and var epsilon-amino caproic acid.