Near stoichiometric, irreversible inactivation of bacterial collagenases by o-chloranil (3,4,5,6-tetrachloro-1,2-benzoquinone).

The hydrogen-abstracting quinone derivative 3,4,5,6-tetrachloro-1,2-benzoquinone (o-chloranil) caused a strong, near stoichiometric, irreversible inactivation of the collagenases from Bacillus cereus, Clostridium histolyticum and Achromobacter iophagus. p-Chloranil was a weaker inactivator. o-Chloranil reacted rapidly with a site that affected substrate binding. Amino acid analyses of native and totally inactivated enzymes, and the pH-profile of inactivation suggest that the dissociated form of a tyrosine residue was modified.