Incorporation of Manganese Complexes into Xylanase: New Artificial Metalloenzymes for Enantioselective Epoxidation

Here we report the best artificial metalloenzyme to date for the selective oxidation of aromatic alkenes; it was obtained by noncovalent insertion of Mn III ‐ meso ‐tetrakis( p ‐carboxyphenyl)porphyrin [Mn(T p CPP), 1 ‐Mn] into a host protein, xylanase 10A from Streptomyces lividans (Xln10A). Two metallic complexes— N , N′ ‐ethylene bis(2‐hydroxybenzylimine)‐5,5′‐dicarboxylic acid Mn III [(Mn‐salen), 2 ‐Mn] and 1 ‐Mn—were associated with Xln10A, and the two hybrid biocatalysts were characterised by UV–visible spectroscopy, circular dichroism and molecular modelling. Only the artificial metalloenzyme based on 1 ‐Mn and Xln10A was studied for its catalytic properties in the oxidation of various substituted styrene derivatives by KHSO 5 : after optimisation, the 1 ‐Mn ‐ Xln10A artificial metalloenzyme was able to catalyse the oxidation of para ‐methoxystyrene by KHSO 5 with a 16 % yield and the best enantioselectivity (80 % in favour of the R isomer) ever reported for an artificial metalloenzyme.