Comparison of the Binding of Reversible Inhibitors to Human Butyrylcholinesterase and Acetylcholinesterase: A Crystallographic, Kinetic and Calorimetric Study

Abstract

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) hydrolyze the neurotransmitter acetylcholine and, thereby, function as coregulators of cholinergic neurotransmission. Although closely related, these enzymes display very different substrate specificities that only partially overlap. This disparity is largely due to differences in the number of aromatic residues lining the active site gorge, which leads to large differences in the shape of the gorge and potentially to distinct interactions with an individual ligand. Considerable structural information is available for the binding of a wide diversity of ligands to AChE. In contrast, structural data on the binding of reversible ligands to BChE are lacking. In a recent effort, an inhibitor competition approach was used to probe the overlap of ligand binding sites in BChE. Here, we extend this study by solving the crystal structures of human BChE in complex with five reversible ligands, namely, decamethonium, thioflavin T, propidium, huprine, and ethopropazine. We compare these structures to equivalent AChE complexes when available in the protein data bank and supplement this comparison with kinetic data and observations from isothermal titration calorimetry. This new information now allows us to define the binding mode of various ligand families and will be of importance in designing specific reversible ligands of BChE that behave as inhibitors or reactivators.

Design, Synthesis, Molecular Docking, and Cholinesterase Inhibitory Potential of Phthalimide‐Dithiocarbamate Hybrids as New Agents for Treatment of Alzheimer's Disease

“…As the prosthetic group and the co‐factors are not directly involved in ChE inhibition, so they were totally removed before docking investigation. Except for the four structural waters molecule in the AChE and BuChE active site, which bridge the receptor important residues by way of H‐bonds and conserve among other specious, the rest of the water molecules were removed from the enzymes crystallographic structures . The 2D structures of the selected compounds were drawn in Marvin 15.10.12.0 program (http://www.chemaxon.com) and converted into pdb.…”

“…Except for the four structural waters molecule in the AChE and BuChE active site, which bridge the receptor important residues by way of H-bonds and conserve among other specious, the rest of the water molecules were removed from the enzymes crystallographic structures. [28] The 2D structures of the selected compounds were drawn in Marvin 15.10.12.0 program (http://www.chemaxon.com) and converted into pdb. The Protein Preparation Wizard and the LigPrep module were used to prepare protein and ligand structure properly.…”

Arylaminopropanone Derivatives as Potential Cholinesterase Inhibitors: Synthesis, Docking Study and Biological Evaluation

“…Different kinetic, crystallographic or calorimetric studies indicate that the active site of both cholinesterases (ChEs) contains two subsites, the 'esteratic' and 'anionic' subsites, corresponding to the catalytic machinery and the choline-binding pocket [12,13]. The catalytic triad that forms the active site consists of Ser, Glu and His [11,14,15].…”

“…They are classified as the pseudo-irreversible inhibitors, as the inhibition of the enzyme is time-dependent. Carbamate moiety forms a complex with the serine residue of the catalytic triad [13]. The non-carbamate part of the ligand is responsible for selectivity and binding dynamics [19].…”

Identification of embelin, a 3‐undecyl‐1,4‐benzoquinone from Embelia ribes as a multitargeted anti‐Alzheimer agent

“…The crystal structures of human AChE (PDB ID: 4EY7)(Cheung et al, 2012), human BChE (PDB ID: 6EP4)(Rosenberry et al, 2017) and BACE-1 (PDB: 4B05)(Jeppsson et al, 2012) were retrieved from protein data bank and were subjected to protein preparation wizard facility under default conditions implemented in Maestro v9.0 and Impact program v5.5 (Schrodinger, Inc., New York, NY, 2009). The prepared proteins were further utilized to construct grid file by selecting co-crystallized ligand as centroid of grid box.…”