This paper reports investigations of the binding of H2 and N2 at intact FeMo-co, using density functional simulations of a large 486 atom relevant portion of the protein, resulting in 27 new structures containing H2 and/or N2 bound at the exo and endo coordination sites of the participating Fe atoms, Fe2 and Fe6. 
density functional simulations
This paper reports investigations of the binding of H2 and N2 at intact FeMo-co, using density functional simulations of a large 486 atom relevant portion of the protein, resulting in 27 new structures containing H2 and/or N2 bound at the exo and endo coordination sites of the participating Fe atoms, Fe2 and Fe6.  Binding energies and transition states for association/dissociation are determined, and trajectories for the approach, binding and separation of H2/N2 are described, including diffusion of these small molecules through proximal protein.  Seven N2 structures and three H2 structures have negative binding free energies, which include the estimated entropy penalties for binding of N2, H2 from proximal protein. 
Protein