New Enzyme Models of Chloroperoxidase: Improved Stability and Catalytic Efficiency of Iron Porphyrinates Containing a Thiolato Ligand

Article abstract of DOI:10.1002/hlca.19980810554

The heme-thiolate protein chloroperoxidase (CPO) catalyzes the chlorination of activated C-H bonds. A reaction mechanism is proposed for this enzymatic transformation (Scheme 1), and a new iron(III) porphyrinate complex 13 is synthesized containing pentafluorophenyl groups at two meso-positions and a thiophenolato ligand coordinating to the Fe-atom (Schemes 2 and 3). Due to the presence of the electron-withdrawing substituents, the catalyst 13 is appreciably resistant to oxidants (HOCl) and chlorinates, e.g., monochlorodimedone (5), with turnover numbers up to 1530. The redox potential of 13, E₀ = - 134 mV, and the Soret band (λ_max 448 nm) of the CO adduct of the reduced state of 13 are close to the corresponding values of the enzyme CPO.