Figure 2.

Structural study of the active site of cpOYE303 (PBD: 4RNV) with key amino acid side chains (orange), FMN (white), and substrate analog p-hydroxybenzaldehyde (HBA; gray). (A) In two of the four protein complexes per asymmetric unit, the best fit to the observed electron density orients the aldehyde group of HBA in hydrogen-bonding distance to H191 and N194, whereas in the other two complexes (B), the ligand is flipped with its hydroxyl moiety pointing toward H191 and N194, as seen for OYE1.³³ The gray mesh represents the 2mFo-DFc map contoured at the 1.0 σ level for key protein side chains, FMN and HBA. Hydrogen bonding distances (in angstroms) are indicated.