Rapid purification of a high-affinity plasminogen activator from human blood plasma by specific adsorption on fibrin/Celite.

A preparation of fibrin precipitated over a solid Celite (diatomaceous earth) matrix that selectively binds 50-70% of the plasminogen activator present in human blood plasma is described. Affinity chromatography of plasma on fibrin/Celite followed by gel filtration led to a 29,000-fold purification of the plasminogen activator. The activator, referred to as the high-affinity plasminogen activator, is characterized by its ability to be strongly adsorbed by fibrin. Smaller amounts of other plasminogen activators and essentially all plasminogen were not bound to fibrin. The high-affinity plasminogen activator is a single-chain unstable protease with a molecular weight of 65,000-70,000. The high-affinity plasminogen activator has a low specific activity (500 CTA units/mg) compared to tissue or urine plasminogen activators (100,000-200,000 CTA units/mg) (CTA, Committee on Thrombolytic Agents).