The Effect of Lumbrokinase, a Trypsin-Like Enzyme from Lumbricus rubellus, on Human Blood Cells

Summary

Lumbrokinase (LK), a trypsin-like enzyme, was efficiently purified from a crude preparation of earthworm (Lumbricus rubellus). The purification procedure was as follows: dissolving crude powder in saline for 3 days; 30%-60% ammonium sulfate gradient fractionation of the soluble fraction; and column chromatography on DEAE-cellulose anion exchange and then p-aminobenzamidine sepharose 6B. Lumbrokinase has a molecular weight of 34.2 kDa, is not dependent on metal ions, is heat-stable, and has a very broad optimal pH range. To examine whether LK hydrolyzed fibrin directly without human blood cell damage, various human blood cells were prepared for characterization of LK activity. The hemolysis of erythrocytes was assayed using a UV spectrophotometer, the degradation pattern of plasma proteins was assessed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the lysis of protein constituents of platelet-rich plasma and platelets (platelets were separated by Bio-gel A-50 gel filtration) was measured. To investigate whether LK causes spontaneous platelet aggregation, the effect of antiaggregation by adenosine diphosphate (ADP) was measured using an aggregometer. It was shown that, in spite of its proteolytic activity, LK did not cause lysis of erythrocytes, or excessive degradation of protein in plasma, platelets, or platelet-rich plasma. Nor did LK cause spontaneous platelet aggregation. The antiaggregation effect by ADP was not observed.