Artificial Hydrogenases Based on Cobaloximes and Heme Oxygenase

• Published in: ChemPlusChem
• Main Authors: Bacchi, Marine, Veinberg, Elias, Field, Martin J., Niklas, Jens, Matsui, Toshitaka, Tiede, D. M., Poluektov, Oleg G., Ikeda‐Saito, Masao, Fontecave, Marc, Artero, Vincent
• Other Authors: U.S. Department of Energy, Office of Science, Argonne National Laboratory
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: Sperm whale
• Online Access: http://dx.doi.org/10.1002/cplu.201600218; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fcplu.201600218; https://onlinelibrary.wiley.com/doi/pdf/10.1002/cplu.201600218; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/cplu.201600218; https://chemistry-europe.onlinelibrary.wiley.com/doi/am-pdf/10.1002/cplu.201600218

Abstract The insertion of cobaloxime catalysts in the heme‐binding pocket of heme oxygenase (HO) yields artificial hydrogenases active for H 2 evolution in neutral aqueous solutions. These novel biohybrids have been purified and characterized by using UV/visible and EPR spectroscopy. These analyses revealed the presence of two distinct binding conformations, thereby providing the cobaloxime with hydrophobic and hydrophilic environments, respectively. Quantum chemical/molecular mechanical docking calculations found open and closed conformations of the binding pocket owing to mobile amino acid residues. HO‐based biohybrids incorporating a {Co(dmgH) 2 } (dmgH 2 =dimethylglyoxime) catalytic center displayed up to threefold increased turnover numbers with respect to the cobaloxime alone or to analogous sperm whale myoglobin adducts. This study thus provides a strong basis for further improvement of such biohybrids, using well‐designed modifications of the second and outer coordination spheres, through site‐directed mutagenesis of the host protein.