Fig. 8: Form 1 crystal structures of the TtCBD-H132A variant.

a Superposition of wild type D^O2 (PDB 8C31 green) and D^O2-H132A (PDB 8C35 orange) models showing residues and AdoCbl binding. b Electron density of bound tetracoordinate cobalamin in I^anaer-H132A structure. The grey mesh depicts the composite omit 2F_o-F_c density contoured at 1.5 σ. c Comparison of corrin ring position in wild-type D^O2 (green), I^anaer (blue) and I^anaer-H132A (grey) structures. The red mesh shows the anomalous density for Co atom contoured at 3.0 σ. d The I^O2-H132A structure shows a water ligated hexa-coordinated His177-Co(III)-H₂O.