Abstract
Nitrogenase is a two-component enzyme that catalyzes the nucleotide-dependent reduction of N 2 to 2NH 3. 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 N 2, 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.
Original language | English (US) |
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Pages (from-to) | 19-25 |
Number of pages | 7 |
Journal | Current Opinion in Chemical Biology |
Volume | 16 |
Issue number | 1-2 |
DOIs | |
State | Published - Apr 2012 |
ASJC Scopus subject areas
- Analytical Chemistry
- Biochemistry