... cofactor; FeFeco, iron–iron cofactor; Rc1Mo, MoFe protein of R. capsulatus;Rc1Fe,FeFeproteinofR. capsulatus;Rc2Mo,Fepro-tein of the Mo nitrogenase of R. capsulatus;Rc2Fe, Fe protein of ... FeFeprotein preparations in view of the lability of the proteineven in the presence of only trace amounts of oxygen [8].For the sake of direct comparison, MoFe protein sampleswere treated ... reduction of thesemireduced to the reduced and EPR silent state of theFeMo cofactor [45].DISCUSSIONThe FeMo cofactor, one of the two unique metal clusterspresent in the MoFe protein component of...