The intriguing enhancement of chloroperoxidase mediated one-electron oxidations by azide, a known active-site ligand

Azide is a well-known inhibitor of heme–enzymes. Herein, we report the counter-intuitive observation that at some concentration regimes, incorporation of azide in the reaction medium enhances chloroperoxidase (CPO, a heme–enzyme) mediated one-electron abstractions from several substrates. A diffusible azidyl radical based mechanism is proposed for explaining the phenomenon. Further, it is projected that the finding could have significant impact on routine in situ or in vitro biochemistry studies involving heme–enzyme systems and azide.

► Azide is a well known heme–enzyme active site ligand and inhibitor.
► Herein, azide is reported to enhance a set of heme–enzyme mediated reactions.
► This effect is disconnected from native enzyme–azide binding.
► Azide could enhance heme–enzyme reactions via a newly proposed mechanism.
► Azide contained in reagents could impact reaction outcomes in redox biochemistry.