Evidence for the formation of a Mo-H intermediate in the catalytic cycle of formate dehydrogenase.

Matteo Tiberti, Elena Papaleo, Nino Russo, Luca De Gioia, Giuseppe Zampella

Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy.

Inorganic chemistry 2012 Aug 6

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DFT/BP86/TZVP and DFT/B3LYP/TZVP have been used to investigate systematically the reaction pathways associated with the H-transfer step, which is the rate-determining step of the reaction HCOO(-) ⇄ CO(2) + H(+) + 2e(-), as catalyzed by metalloenzyme formate dehydrogenase (FDH). Actually, the energetics associated with the transfer from formate to all H (proton or hydride) acceptors that are present within the FDH active site have been sampled. This study points to a viable intimate mechanism in which the metal center mediates H transfer from formate to the final acceptor, i.e. a selenocysteine residue. The Mo-based reaction pathway, consisting of a β-H elimination to metal with concerted decarboxylation, turned out to be favored over previously proposed routes in which proton transfer occurs directly from HCOO(-) to selenocysteine. The proposed reaction pathway is reminiscent of the key step of metal-based catalysis of the water-gas shift reaction.

Citation

Matteo Tiberti, Elena Papaleo, Nino Russo, Luca De Gioia, Giuseppe Zampella. Evidence for the formation of a Mo-H intermediate in the catalytic cycle of formate dehydrogenase. Inorganic chemistry. 2012 Aug 6;51(15):8331-9