Plasminogen purification from serum through affinity membranes

The use of plasmin in some eye treatment and, in particular, as a facilitator for eye surgery to prevent retinal detachment is beneficial for the patient and entails less surgical risks than conventional vitrectomy. Plasmin is obtained by activation of plasminogen using a variety of enzymes, including tissue plasminogen activator, urokinase and streptokinase. The isolation of plasminogen from blood is normally performed with bead-based affinity chromatography however, affinity membranes are ideally suited for this application since they can be easily packed in small units providing a fast and economic process. In this work, we prepared affinity membranes for plasminogen purification using L-lysine as affinity ligand. To this aim regenerated cellulose membranes were used as a support for ligand immobilization. The efficiency of L-lysine coupling was inspected by applying different binding protocols and the immobilization yield was studied as a function of the reaction conditions. The membranes have been characterized in batch and in complete chromatographic cycles using bovine and human serum as test probes. The results obtained indicate that the L-lysine affinity membranes are a promising alternative for the purification of plasminogen.