Patent ID: 8148105

Claim:
A method for producing a self-activating Hordeum vulgare cysteine endoprotease B, isoform 2 proenzyme (proEP-B2), the method comprising: producing proEP-B2 in a fermentation reaction with a microbial host; extracting inclusion bodies containing proEP-B2 from said microbial host, solubilizing the inclusion bodies in 5 M or greater urea to produce solubilized, denatured proEP-B2; purifying said solubilized, denatured, proEP-B2; and refolding said purified, solubilized, denatured pro-EP-B2 by rapid dilution into buffer comprising not more than 0.7 M urea under constant stirring wherein the protein concentration during refolding is maintained at greater than 500 μg/ml to provide a proEP-B2 enzyme composition capable of self-activation at acidic pH.