Figure 1.

Cartoon representation of TcAChE in complex with E2020 in a monomer and dimer. The crystal structure of TcAChE in complex with E2020 (pdb code: 1eve) was used. (a) The active-site gorge of TcAChE is shown as a grey molecular surface. The bound E2020 is shown as ball-and-sticks. Two “bottleneck” residues, Y121 and F330, are shown as sticks. Five subdomains surrounding the active-site gorge are highlighted with yellow (the Ω-loop, residues 67–94), green (S1, residues 114–150), cyan (S2, residues 225–296), blue (S3, residues 324–400), and magenta (S4, residues 428–450). (b) Interactions between 12 residues (sticks) and E2020 (spheres), calculated by the program LigPlot⁵⁰. (c) A dimer of TcAChE-E2020. The subdomains (Ω-loop, S1, S2, S3 and S4) are shown with same colors as they are in panel a. (d) The dimer interface is mainly constructed by four helices: H₁ and H₂ from chain A, and H₃ and H₄ from chain B. H₁ or H₃ (residues 361–381) is a helix from the subdomain S3, while H₂ or H₄ (residues 514–535) is a C-terminal helix. Inter-chain interacting residues, predicted by LigPlot, are shown as sticks. Hydrogen bonds are shown as red lines.