Purification and characterization of a cysteine proteinase from eggs of the cotton boll worm, Helicoverpa armigera

High proteolytic activities were detected from oocytes of the cotton boll worm, Helicoverpa armigera at pH 3–4. The proteolytic activities can be inhibited by TosLysCH2Cl, iodoacetate, E-64, chymostatin, but not by TosPheCH2Cl, EDTA, iPr2P-F and pepstatin. It is suggested that a cysteine proteinase might exist in the oocytes. By DEAE-cellulose and DEAE-Toyopearl chromatography, a proteinase was purified from the oocytes. The molecular mass of the proteinase was estimated at 30 kDa by SDS-PAGE. This proteinase effectively hydrolyzed both bovine serum albumin and bovine hemoglobin at pH 3–4. The most effective temperature for the proteinase is 30–50°C. The activity of the proteinase can be inhibited by TosLysCH2Cl, iodoacetate, iPr2P-F, E-64, chymostatin and leupeptin. Because E-64 is a specific inhibitor of cysteine proteinase, the purified proteinase is likely to be a cysteine proteinase. Also, this proteinase is inhibited by iPr2P-F, a specific inhibitor of serine proteinase, which suggests that serine residue is also necessary for its activiation of the proteinase.