Setaria cervi: in vitro released collagenases and their inhibition by Wuchereria bancrofti infected sera

In vitro released products of adult Setaria cervi females, microfilariae and extracts showed considerable amounts of collagenase activity. On the basis of per mg protein released in vitro, the products of both microfilariae and adult females exhibited comparable activity but this was much higher than that of extract of microfilariae and adult females. Two collagenase enzymes with molecular masses of 50 kDa and 70 kDa were separated using DEAE-sepharose CL6B and Sephadex G-100 column chromatography. The 50 kDa and 70 kDa collagenase exhibited pH optima of 5.2 and 7.0, respectively. Considering specific activity, the 50 kDa enzyme was found to contribute about ten times more collagenase activity as compared to the 70 kDa enzyme. An inhibition study revealed obvious differences between them. Thiol group inhibitors such as N-ethylmaleimide and leupeptin inhibited the 50 kDa enzyme but this was strongly activated by dithiothreitol, a thiol group stabilizer. Alternatively, the 70 kDa enzyme showed a sensitivity to a metal chelator and a serine group inhibitor indicating its metalloserine protease nature. The antifilarial drug diethylcarbamazine did not demonstrate any inhibition under in vitro conditions. Both enzymes were significantly inhibited by antibody IgG separated from Wuchereria bancrofti infected human sera, showing a possible immunoprotective role.