Evidence for the Formation of a Mo鈥揌 Intermediate in the Catalytic Cycle of Formate Dehydrogenase

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• 作者：Matteo Tiberti ; Elena Papaleo ; Nino Russo ; Luca De Gioia ; Giuseppe Zampella
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：August 6, 2012
• 年：2012
• 卷：51
• 期：15
• 页码：8331-8339
• 全文大小：484K
• 年卷期：v.51,no.15(August 6, 2012)
• ISSN：1520-510X

文摘

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^{鈥?/sup> CO₂ + H+ + 2e鈥?/sup>, 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 尾-H elimination to metal with concerted decarboxylation, turned out to be favored over previously proposed routes in which proton transfer occurs directly from HCOO鈥?/sup> to selenocysteine. The proposed reaction pathway is reminiscent of the key step of metal-based catalysis of the water鈥揼as shift reaction.}