Figure 2.

AChE2 ligand-binding site interaction with the oxidized acaricide diazoxon. Diazinon is metabolically oxidized by tick enzymes, enhancing its toxic effect on AChE2 which interacts with the acaricide at the ligand-binding site via hydrogen bonds. (A) Diazoxon highlighted in yellow, which interacts by means of hydrogen bonds with amino acids D478 and G477 in close proximity to H476, an important component of the AChE2 catalytic triad. (B) Isolate C1 AChE2 interacts with L480 and H476. (C) Isolate C2 AChE2 interacts directly with diazoxon via ionic bonds; additionally, the acaricide also interacts via hydrogen bonds with R110 and N359.