MIT Chem papers explain why molybdenum nitrogenases bind N2 more efficiently

Two MIT studies in the journal Chem examine why molybdenum-containing nitrogenases convert nitrogen gas to ammonia more efficiently than other metal classes, phys.org reported. Nitrogenases that fix atmospheric N2 vary by metal content; molybdenum versions are the most efficient, and the papers probe the iron-sulfur cofactor chemistry behind that gap. In one paper, researchers swapped metals into synthetic iron-sulfur clusters and measured nitrogen binding. Only cofactors with a large metal atom such as molybdenum or tungsten strongly bound N2; smaller metals including vanadium, chromium, or iron did not and favored other reactions. A second paper found molybdenum doping made it easier for neighboring iron centers to donate electrons through back-bonding, a step needed to reduce difficult substrates related to N2. The work, with DOIs 10.1016/j.chempr.2026.103133 and 10.1016/j.chempr.2026.103134, is framed as guidance for engineered enzymes or synthetic catalysts that could produce ammonia with less reliance on industrial fertilizer chemistry.