The enzyme nitrogenase couples adenosine triphosphate (ATP) hydrolysis to the multi-electron reduction of atmospheric dinitrogen into ammonia. Despite extensive research, the mechanistic details of ATP-dependent energy transduction and dinitrogen reduction by nitrogenase are not well understood, requiring new strategies to monitor its structural dynamics during catalytic action. Here we report cryogenic electron microscopy structures of the nitrogenase complex prepared under enzymatic turnover conditions. We observe that asymmetry governs all aspects of nitrogenase mechanism including ATP hydrolysis, protein-protein interactions, and catalysis. Conformational changes near the catalytic iron-molybdenum cofactor are correlated with the nucleotide-hydrolysis state of the enzyme.

中文翻译：

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催化周转条件下制备的固氮酶复合物的结构

固氮酶将三磷酸腺苷 (ATP) 水解与大气二氮多电子还原成氨结合起来。尽管进行了广泛的研究，但 ATP 依赖性能量转导和固氮酶还原二氮的机制细节尚不清楚，需要新的策略来监测催化作用期间的结构动态。在这里，我们报告了在酶周转条件下制备的固氮酶复合物的低温电子显微镜结构。我们观察到不对称性控制着固氮酶机制的各个方面，包括 ATP 水解、蛋白质-蛋白质相互作用和催化。催化铁钼辅因子附近的构象变化与酶的核苷酸水解状态相关。