Unspecific peroxygenases immobilized on Pd-loaded three-dimensional ordered macroporous (3DOM) titania photocatalyst for photo-enzyme integrated catalysis

Abstract

The selective oxyfunctionalization of C-H and CC bonds is highly important and catalyzed by unspecific peroxygenases (UPOs) which suffer from inactivation by hydrogen peroxide (H2O2). Herein, photo-enzyme integrated catalysts were constructed by immobilizing AaeUPO as cross-linked enzyme aggregates (CLEAs) in Pd-loaded three-dimensional ordered macroporous titania (3DOM TiO2) with in situ photocatalytic H2O2 production. The prepared AaeUPO@3DOM TiO2-Pd obtained higher catalytic efficiency compared with CLEAs-AaeUPO. The conversion of ethylbenzene to (R)-1-phenethyl alcohol was significantly improved, reaching 99 % compared with free enzyme (38 %) and CLEAs-AaeUPO (49 %), with ee value of > 99 %. AaeUPO@3DOM TiO2-Pd exhibited good stability and reusability attributed to the protection of macropores and in situ H2O2 production. By using the designed 3DOM platform for photocatalysis and enzyme immobilization, the in situ photocatalytic generation of H2O2 was highly efficient, and the monodisperse CLEAs-AaeUPO in the macropores facilitated the contact of substrate and enzyme, thus obtaining excellent photo-enzyme coupled catalysis.