Postbiosynthetic modification of a precursor to the nitrogenase iron–molybdenum cofactor

Abstract

Significance Biological metalloclusters catalyze many of the global-scale redox interconversions of the elements, such as the nitrogenase-mediated reduction of N 2 to bioavailable NH 3 . Understanding the mechanisms of these transformations requires knowledge of how the clusters’ individual metal ions contribute to their physical properties and chemical reactivity. This has been an ongoing challenge for the Fe–S clusters of nitrogenases, which feature many Fe sites that are difficult to distinguish spectroscopically. Using the L-cluster (a key biosynthetic precursor to the Mo nitrogenase catalytic cofactor) as a case study, we show that chemical modification of nitrogenase cofactors is a promising strategy for simplifying their spectroscopic analysis and relating their electronic structures to their geometric structures.