Novel haloperoxidase substrates. Alkynes and cyclopropanes.

Two new substrate classes that can be halogenated by haloperoxidase have been discovered. The enzymatic halogenation of alkynes yields alpha-halogenated ketones, and the enzymatic halogenation of cyclopropanes yields alpha, gamma-halohydrins. The general reaction scheme proposed involves the initial formation of hypohalous acid as the key intermediate. This proposed mechanism, based upon observed differences in product selectivities, is opposite of that proposed previously, based upon observed differences in substrate selectivities. The biosynthetic implications of these novel haloperoxidase reactions are also discussed.