Figure 1.

Highly conserved bimetallic active site of [NiFe] hydrogenases. Numbering refers to the amino acid sequence for E. coli Hyd-1, and we use this numbering throughout. Panel (A) shows two different orientations of the same structure to highlight the coordination geometry around the metals. Panel (B) presents the same structure, with the position of additional highly conserved amino acid residues shown. The active site structure is representative, but taken from crystallographic data for E. coli Hyd-1, PDB code 3USE, and prepared using Pymol.⁷