Studies of a proteolytic enzyme from Schistosoma mansoni.

The presence of a proteolytic enzyme has been demonstrated in ground-up preparations of Schistosoma mansoni. A twenty-fold purification has been achieved by ultracentrifugation at pH 3.0; the enzyme has an optimum pH of 3.9 and a marked substrate specificity for haemoglobin. No significant proteolysis was observed either with whole serum at pH values of 3.9, 6.0 or 8.0, or with isolated serum proteins at pH ranges between 2.5 and 7.7. The evidence is discussed that this enzyme may be located in the intestine of the schistosomes and that it is, at least in part, responsible for the supply of amino acids to the organisms.