New aspects of H2 activation by nickel–iron hydrogenase

✍ Scribed by Maria Pavlov; Margareta R. A. Blomberg; Per E. M. Siegbahn

• Book ID: 101254844
• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 240 KB
• Volume: 73
• Category: Article
• ISSN: 0020-7608
• DOI: 10.1002/(sici)1097-461x(1999)73:2<197::aid-qua13>3.0.co;2-r

✦ Synopsis

The density functional theory DFT method B3LYP has been used to investigate the catalytic mechanism of Ni᎐Fe hydrogenases in light of new experimental data on the structure. The reaction pathway suggested in previous theoretical work is now slightly modified. In the reaction mechanism proposed in the present study, one of the hydrogens from H appears as a hydride bridge between Ni and Fe in the reduced 2 form. The bridging hydride brings Ni and Fe closer together, which results in an interatomic distance of 2.56 A, which is a shortening from the calculated oxidized form of 0.28 A. A shortening of the Ni᎐Fe distance in the reduced form as compared to the oxidized form agrees with the recent experimental X-ray structures. Effects on the reaction mechanisms, due to protonation and deprotonation of the terminal cysteine ligands on Ni and coordination of a water molecule on Ni have also been studied. Solvent effects have been included using dielectric cavity methods.