Fig. 6: Mutagenesis of the I-helix catalytic residues.
From: Structural insights into S-lignin O-demethylation via a rare class of heme peroxygenase enzymes
Ribbon and stick diagrams showing the I-helix of a SyoA substrate-free (PDB: 8u09), b SyoA syringol-bound (PDB: 8u19), and c GcoA guaiacol-bound (PDB: 5ncb). The I-helix is highlighted showing the key catalytic residues Gln252/Gln248 and Glu253/Glu249 (stick representation) and hydrogen bonding interactions (black dashed lines) to surrounding residues and water molecules (small red spheres). d, e HPLC analysis of the hydrogen peroxide driven O-demethylation of syringol by SyoA and guaiacol by GcoA compared to the mutants; chromatogram colors are defined in the key. Despite being folded, and competent for substrate binding, mutation of Gln and/or Glu resulted in loss of peroxygenase activity in both SyoA and GcoA. *Denotes non-enzymatic oxidation product of 3-methoxycatechol.
