Gas access to the active site of Ni-Fe hydrogenases probed by X-ray crystallography and molecular dynamics

The 2.54 A resolution structure of Ni-Fe hydrogenase has revealed the existence of hydrophobic channels connecting the molecular surface to the active site. A crystallographic analysis of xenon binding together with molecular dynamics simulations of xenon and H2 diffusion in the enzyme interior suggest that these channels serve as pathways for gas access to the active site.