Inhibitor: The enzyme is inactivated by DIFP or PMSF (PMSF used at final concentration 5 mM. ). However, it is not inhibited by EDTA , iodoacetic acid, trypsin-specific inhibitor TLCK, chymotrypsin-specific inhibitor TPCK, and p-chloromercuribenzoate.
Activator: To stimulate proteinase K activity, 1-5 mM Ca2+ can be added. Optimization using activators can increase proteinase activity significantly. Enzyme activity will be reduced by 25% when calcium is removed by addition of EDTA. Enzyme activity will be reduced by 80% if the EDTA-Ca2+ complex is removed from the enzyme solution by gel filtration, while it can be partially restored by addition of excess Ca2+.