Affinity-chromatographic purification of human α2-antiplasmin

Abstract

A new simple and efficient purification method for α2-antiplasmin is described that is based on the interaction between α2-antiplasmin and a fragment from elastase-digested plasminogen constituting the three N-terminal triple-loop structures in the plasmin A-chain (LBSI). After a single-step adsorption of the α2-antiplasmin from plasminogen-depleted plasma to LBSI-Sepharose and elution with 6-aminohexanoic acid, an 80-90% pure preparation with a yield of 50-60% is obtained. The major impurity is fibrinogen, which can easily be removed by gel filtration, and, as a result, a homogeneous fully active α2-antiplasmin preparation is obtained that has the same properties as previously described for α2-antiplasmin. Evidence is put forward that a form of α2-antiplasmin with les affinity for the lysine-binding sites in plasminogen may exist, even in unfractionated plasma.