Biosciences Center, National Renewable Energy Laboratory, Golden, CO 80401, USA.
Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322, USA.
Science. 2016 Apr 22;352(6284):448-50. doi: 10.1126/science.aaf2091.
The splitting of dinitrogen (N2) and reduction to ammonia (NH3) is a kinetically complex and energetically challenging multistep reaction. In the Haber-Bosch process, N2 reduction is accomplished at high temperature and pressure, whereas N2 fixation by the enzyme nitrogenase occurs under ambient conditions using chemical energy from adenosine 5'-triphosphate (ATP) hydrolysis. We show that cadmium sulfide (CdS) nanocrystals can be used to photosensitize the nitrogenase molybdenum-iron (MoFe) protein, where light harvesting replaces ATP hydrolysis to drive the enzymatic reduction of N2 into NH3 The turnover rate was 75 per minute, 63% of the ATP-coupled reaction rate for the nitrogenase complex under optimal conditions. Inhibitors of nitrogenase (i.e., acetylene, carbon monoxide, and dihydrogen) suppressed N2 reduction. The CdS:MoFe protein biohybrids provide a photochemical model for achieving light-driven N2 reduction to NH3.
氮气（N2）的分裂和还原为氨（NH3）是一个动力学复杂且能量上具有挑战性的多步反应。在哈伯-博世工艺中，N2 的还原是在高温高压下完成的，而氮酶固氮则在环境条件下利用三磷酸腺苷（ATP）水解产生的化学能进行。我们表明，硫化镉（CdS）纳米晶体可用于敏化氮酶钼铁（MoFe）蛋白，其中光捕获取代 ATP 水解以驱动 N2 酶促还原为 NH3，每分钟的周转率为 75 次，在最佳条件下，氮酶复合物的 ATP 偶联反应速率为 63%。氮酶抑制剂（即乙炔、一氧化碳和氢气）抑制了 N2 的还原。CdS:MoFe 蛋白生物杂种为实现光驱动 N2 还原为 NH3 提供了一个光化学模型。
