Cleaving the N,N Triple Bond: The Transformation of Dinitrogen to Ammonia by Nitrogenases - The Metal-Driven Biogeochemistry of Gaseous Compounds in the Environment - page 147

Figure 1 Schematic presentation showing the interaction between the two component proteins
of Mo-nitrogenase during catalysis.

2.1 The Fe Protein and Its Associated Metal Clusters

The Fe protein of Mo-nitrogenase couples the energy derived from ATP hydrolysis
to the transfer of electrons to its redox partner, the MoFe protein. This protein
and its associated [Fe 4 S 4 ] cluster display a number of interesting structural and
spectroscopic features, which are discussed in detail below.

2.1.1 The Polypeptide

The Fe protein of A. vinelandii is encoded by the nifH gene. It is a γ 2 -homodimer

of ~60 kDa, and its two subunits are bridged by a [Fe 4 S 4 ] cluster [ 1 - 4 , 6 - 9 , 26 - 28 ].
Each subunit of the Fe protein contains a Walker A motif (residues 9-16), which
provides the site for the binding and hydrolysis of MgATP [ 26 - 28 ]. While the