Rohde Michael, Laun Konstantin, Zebger Ingo, Stripp Sven T, Einsle Oliver
Institute for Biochemistry, University of Freiburg, Albertstrasse 21, 79104 Freiburg, Germany.
Institute of Chemistry, Technical University of Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany.
Sci Adv. 2021 May 28;7(22). doi: 10.1126/sciadv.abg4474. Print 2021 May.
Besides its role in biological nitrogen fixation, vanadium-containing nitrogenase also reduces carbon monoxide (CO) to hydrocarbons, in analogy to the industrial Fischer-Tropsch process. The protein yields 93% of ethylene (CH), implying a C-C coupling step that mandates the simultaneous binding of two CO at the active site FeV cofactor. Spectroscopic data indicated multiple CO binding events, but structural analyses of Mo and V nitrogenase only confirmed a single site. Here, we report the structure of a two CO-bound state of V nitrogenase at 1.05 Å resolution, with one μ-bridging and one terminal CO molecule. This additional, specific ligand binding site suggests a mechanistic route for CO reduction and hydrocarbon formation, as well as a second access pathway for protons required during the reaction. Moreover, carbonyls are strong-field ligands that are chemically similar to mechanistically relevant hydrides that may be formed and used in a fully analogous fashion.
除了在生物固氮中发挥作用外，含钒固氮酶还能将一氧化碳（CO）还原为碳氢化合物，这类似于工业费托合成过程。该蛋白质产生93%的乙烯（CH），这意味着存在一个碳-碳偶联步骤，该步骤要求在活性位点FeV辅因子上同时结合两个CO。光谱数据表明存在多个CO结合事件，但对钼和钒固氮酶的结构分析仅证实了一个位点。在此，我们报告了钒固氮酶与两个CO结合状态的结构，分辨率为1.05 Å，其中一个是μ-桥连CO分子，一个是末端CO分子。这个额外的特定配体结合位点为CO还原和碳氢化合物形成提供了一种机制途径，以及反应过程中所需质子的第二条进入途径。此外，羰基是强场配体，在化学上与可能以完全类似方式形成和使用的具有机制相关性的氢化物相似。
