Figure 5.

Structure of M. capsulatus (Bath) MDH. (A) αβ protomer. The eight-bladed β sheet propeller motif is colored light blue, and the blades are labeled W1–W8. Auxiliary β strands are colored light pink and α helices blue, including the long α helix of the β subunit. A PQQ ligand (yellow) and Ca²⁺ ion (gray) are located in the cavity of the propeller core fold. (B) Composite omit map generated in Phenix contoured at 1σ showing the cofactors and hydrogen bonding residues. Ligand coordination to the Ca²⁺ ion is shown as solid lines, and hydrogen bonds are shown as dashed lines. (C) α₂β₂ dimer structure with chains C and D colored light and dark green and chains M and N colored light and dark blue.