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 boil worm, Helicoverpa armigera at pH 3-4. The proteolytic activities can be inhibited by TosLysCH(2)Cl, iodoacetate, E-64, chymostatin, but not by TosPheCH(2)Cl, EDTA, iPr(2)P-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 30kDa 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 degrees C. The activity of the proteinase can be inhibited by TosLysCH(2)Cl, iodoacetate, iPr(2)P-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 iPr(2)P-F, a specific inhibitor of serine proteinase, which suggests that serine residue is also necessary for its activation of the proteinase. (C) 1998 Elsevier Science Ltd. All rights reserved.