Cathepsin D, purified from bovine spleen, is inactivated by the unstable inhibitors dithiophosgene and 2,2-dichloro-1,3-dithiacyclobutanone. Inhibition constants are identical for both of the compounds tested: Ki 96.1 μM;k/c0.406. It appears that the active species is 2,2-dichloro-1,3-dithiacyclobutanone, to which dithiophosgene is hydrolysed before cathepsin D inactivation.
