Fig. 1.

Schematic presentations of cofactor-deficient MoFe proteins. The ΔnifB MoFe protein (A) contains two P-clusters (i.e., [Fe₈S₇] clusters); the ΔnifBΔnifZ MoFe protein (B) contains one P-cluster and one P*-cluster (i.e., paired [Fe₄S₄]-like clusters); and ΔnifH MoFe protein (C) contains two P*-clusters. The [Fe₈S₇] and [Fe₄S₄] clusters are represented by gray ovals and cubes, respectively; whereas the vacant cofactor sites are represented by white ovals.