Figure 4

(A) Stereo view of the active sites of LAAO and porcine DAAO (pcDAAO) with the respective FAD cofactors superimposed along the isoalloxazine ring system. (B) Stereo view of the active sites of LAAO and the mirror-image pcDAAO with the AB ligands superimposed. Atoms and bonds are represented as capped sticks, with those corresponding to DAAO being shown in green and those from LAAO shown in red. The modeled His223 rotamer optimally situated to abstract a proton from the amino group from the substrate is shown in cyan. Superimposed AB molecules are shown in magenta. The mirror plane co-incident with the catalytic axis is shown in gray and those atoms involved in catalysis that lie along the mirror plane are enlarged. (C) Stereo representation of the modeled L-phenylalanine substrate within the active site. Amino acid residues, the FAD and L-phenylalanine molecules are shown in yellow, gray and cyan bonds, respectively. Hydrogen bonds are depicted as black dashed lines.