Instantaneous, stoichiometric generation of powerfully reducing states of protein active sites using Eu(ii) and polyaminocarboxylate ligands

Abstract

Addition of an equivalent of a polyaminocarboxylate ligand (L) to a solution of a redox protein and the aqua Eu²⁺ ion results in the instantaneous in situ generation of a very powerful reductant Eu^II–L that can rapidly drive an electron stoichiometrically onto a redox centre having an extremely negative reduction potential (lower than −1 V): this is exemplified by straightforward generation of the super-reduced state of the Fe-protein of nitrogenase.