Figure 1.
Top view of an overlay of three-dimensional structures of the greenbug and human acetylcholinesterase from a perspective looking down onto substrate acetylcholine at the catalytic site.
The C, N, O, and S atoms are colored in yellow/green (human/greenbug), blue, red, and orange, respectively. The theoretical model of the greenbug enzyme and the crystal structure of the human enzyme were obtained from the coordinate files with Protein Data Bank codes of 2HCP and 1B41, respectively.
Figure 2.
Diagram representation of a methanethiosulfonate-bearing inhibitor (red) that reacts with Cys289 of the greenbug acetylcholinesterase (blue) upon its binding at the active site.
Figure 3.
Chemical structures and synthetic schemes for AMTS7–AMTS20 as irreversible inhibitors of the greenbug acetylcholinesterase.
Figure 4.
Cross-section view of the multiple-molecular-dynamics-simulation-refined three-dimensional models of the greenbug and human acetylcholinesterases in complex with AMTS17 and AMTS13, respectively.
Left: The C, N, O, and S atoms are colored in magenta/green (AMTS17/AChE), blue, red, and yellow, respectively. Right: The C, N, O, and S atoms are colored in green/yellow (AMTS13/AChE), blue, red, and yellow, respectively.
Figure 5.
Inhibition of the greenbug and human AChEs by AMTS7–AMTS20.
Extracts of greenbugs and human RBCs in 0.1 M sodium phosphate buffer (see Methods) were exposed to AMTS7–AMTS20 at 6.0 µM for one hour at room temperature. Radiometric assays were used to determine AChE activity in aliquots of treated samples either immediately (empty symbols) or after overnight dialysis with 2 changes of buffer in 100-fold excess (filled symbols). The difference between the paired measurements (i.e., the recovery after dialysis) indicates reversible inhibition.
Table 1.
Reactivation Studies of the Greenbug and Human Acetylcholinesterases (AChEs) Inhibited by AMTS13 Using β-Mercaptoethanol (BME) That Can Reverse the AMTS13 Inhibition and Concomitantly Denature the Disulfide-Containing AChEs.