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, David M., Poluektov, Oleg G., Ikeda-Saito, Masao, Fontecave, Marc, Artero, Vincent
• Language: unknown
• Published: 2021
• Subjects: 37 INORGANIC; ORGANIC; PHYSICAL; AND ANALYTICAL CHEMISTRY; Sperm whale
• Online Access: http://www.osti.gov/servlets/purl/1351308; https://www.osti.gov/biblio/1351308; https://doi.org/10.1002/cplu.201600218

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. Here, 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.