固氮酶
氧化还原
电子转移
辅因子
化学
钼
金属
基质(水族馆)
电子
结晶学
光化学
无机化学
酶
物理
生物化学
固氮
海洋学
有机化学
量子力学
地质学
氮气
作者
Lance C. Seefeldt,Brian M. Hoffman,Dennis R. Dean
标识
DOI:10.1016/j.cbpa.2012.02.012
摘要
Nitrogenase is a two-component enzyme that catalyzes the nucleotide-dependent reduction of N2 to 2NH3. This process involves three redox-active metal-containing cofactors including a [4Fe-4S] cluster, an eight-iron P cluster and a seven-iron plus molybdenum FeMo-cofactor, the site of substrate reduction. A deficit-spending model for electron transfer has recently been proposed that incorporates protein conformational gating that favors uni-directional electron transfer among the metalloclusters for the activation of the substrate-binding site. Also reviewed is a proposal that each of the metal clusters cycles through only two redox states of the metal-sulfur core as the system accumulates the multiple electrons required for substrate binding and reduction. In particular, it was suggested that as FeMo-cofactor acquires the four electrons necessary for optimal binding of N2, each successive pair of electrons is stored as an Fe-H--Fe bridging hydride, with the FeMo-cofactor metal-ion core retaining its resting redox state. We here broaden the discussion of stable intermediates that might form when FeMo-cofactor receives an odd number of electrons.
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