Purification and characterization of two fibrinolysins from the midgut of adult female Glossina morsitans centralis.

1. Adult female tsetse flies (Glossina morsitans centralis) have at least five midgut fibrinolytic proteases, the two most active of which we have purified using DE-52 cellulose. 2. The purified proteases appeared as single bands in sodium dodecylsulphate polyacrylamide gels and had mol. wts of 24,000 and 23,500 and pI values of 6.0 and 5.3, respectively. 3. Both proteases hydrolyse Tosyl-Gly-Pro-Arg-pNA optimally at pH 8.0 (with Km of 20 and 30 microM) and were inhibited by diisopropylfluorophosphate, alpha 1-protease inhibitor, aprotinin, soybean trypsin inhibitor, benzamidine and tosyllysine chloromethylketone. 4. Compared to bovine plasmin, these enzymes digest fibrinogen or fibrin at a slower rate but give similar products. 5. Thus these enzymes are serine proteases similar to the trypsin-like enzymes detected in G. m. morsitans.