Nitrogen gas is abundant in the Earth's atmosphere, but most living organisms cannot readily use this nitrogen. Only a subset of microbes that have enzymes known as nitrogenases can break nitrogen gas apart and convert it into ammonia. There are three different classes of nitrogenases found in nitrogen-fixing microbes, which vary based on the types of metal that they contain. Nitrogenases that contain the metal molybdenum are the most efficient, and two new studies offer an explanation for why that is. The findings could help guide the design of engineered enzymes or synthetic catalysts that can convert nitrogen gas to ammonia.
The team found that while molybdenum does not directly bind to nitrogen, it helps nearby iron atoms bind to nitrogen more strongly. This is a critical first step in breaking the bond between the two nitrogen atoms that form nitrogen gas. The researchers also found that when molybdenum is included in the cluster, it becomes easier for iron to donate some of its electrons to the N-heterocyclic carbenes, in a process known as back-bonding.
Blogger's Review: This study reveals the secret of nitrogen-processing enzymes, where molybdenum metal atoms play a crucial role. This discovery may have significant implications for future agricultural and industrial production, reducing the dependence on fertilizers and increasing the efficiency of ammonia production. Meanwhile, this research result also provides a new perspective on understanding the nitrogen cycle in nature.