Coordination of Methyl Coenzyme M and Coenzyme M at Divalent and Trivalent Nickel Cyclams: Model Studies of Methyl Coenzyme M Reductase Active Site

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• 作者：Jun-ichi Nishigaki ; Tsuyoshi Matsumoto ; Kazuyuki Tatsumi
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：March 19, 2012
• 年：2012
• 卷：51
• 期：6
• 页码：3690-3697
• 全文大小：440K
• 年卷期：v.51,no.6(March 19, 2012)
• ISSN：1520-510X

文摘

Divalent and trivalent nickel complexes of 1,4,8,11-tetraazacyclotetradecane, denoted as cyclam hereafter, coordinated by methyl coenzyme M (MeSCoM^{鈥?/sup>) and coenzyme M (HSCoM鈥?/sup>) have been synthesized in the course our model studies of methyl coenzyme M reductase (MCR). The divalent nickel complexes Ni(cyclam)(RSCoM)₂ (R = Me, H) have two trans-disposed RSCoM鈥?/sup> ligands at the nickel(II) center as sulfonates, and thus, the nickels have an octahedral coordination. The SCoM2鈥?/sup> adduct Ni(cyclam)(SCoM) was also synthesized, in which the SCoM2鈥?/sup> ligand chelates the nickel via the thiolate sulfur and a sulfonate oxygen. The trivalent MeSCoM adduct [Ni(cyclam)(MeSCoM)₂](OTf) was synthesized by treatment of [Ni(cyclam)(NCCH₃)₂](OTf)₃ with (nBu₄N)[MeSCoM]. A similar reaction with (nBu₄N)[HSCoM] did not afford the corresponding trivalent HSCoM鈥?/sup> adduct, but rather the divalent nickel complex polymer [鈭扤iII(cyclam)(CoMSSCoM)鈭抅_n was obtained, in which the terminal thiol of HSCoM鈥?/sup> was oxidized to the disulfide (CoMSSCoM)2鈥?/sup> by the Ni(III) center.}