A method for producing a refolded, inactive form of recombinantly produced
NS2/3 protease which comprises the steps of: a) purifying the protease
from inclusion bodies in the presence of a chaotropic agent; and b)
refolding the purified protease by contacting it with a reducing agent
and lauryldiethylamine oxide (LDAO) in the presence of reduced
concentration of chaotropic agent or polar additive. The invention
further comprises a method for activating this refolded inactive NS2/3
protease by adding an activation detergent. This method produces large
amounts of the active NS2/3 protease to allow small molecules and ligands
to be screened as potential inhibitors of NS2/3 protease, which may be
useful as therapeutic agents against HCV.