Purification of cysteine proteinases from adult Schistosoma mansoni.

Proteolytic activity against hemoglobin and low molecular weight synthetic substrates has been previously found in homogenates and excretion/secretion products of adult Schistosoma mansoni worms. This activity is stimulated in the presence of thiol compounds and is maximally active at acidic pH. To characterize further this proteolytic activity, lyophilized adult worms were extracted, and proteinases were isolated and purified. From extracts prepared in 0.2 M citrate buffer, pH 4.9, two proteinase species were purified to homogeneity by centrifugation, gel filtration, dialysis, and chromatofocusing chromatography. The proteinases, designated SMw32 and SMw28, have apparent molecular weights (SDS-PAGE) of 31,700 +/- 1400 and 27,800 +/- 1700, respectively. Both are thiol-dependent, acidic endopeptidases that cleave hemoglobin and a synthetic substrate, CBZ-arg-arg-AFC. A statistical comparison of amino acid compositions reveals that the proteinases are highly related.