A Quantum Mechanics/Molecular Mechanics Study of the Protein−Ligand Interaction of Two Potent Inhibitors of Human O-GlcNAcase: PUGNAc and NAG-Thiazoline

O-glycoprotein 2-acetamino-2-deoxy-β-d-glucopyranosidase (O-GlcNAcase) hydrolyzes 2-acetamido-2-deoxy-β-d-glucopyranose (O-GlcNAc) residues of serine/threonine residues of modified proteins. O-GlcNAc is present in many intracellular proteins and appears to have a role in the etiology of several diseases including cancer, Alzheimer’s disease, and type II diabetes. In this work, we have carried out molecular dynamics simulations using a hybrid quantum mechanics/molecular mechanics approach to determine the binding of two potent inhibitors, PUGNAc and NAG, with a bacterial O-GlcNAcase. The results of these simulations show that Asp-401, Asp-298, and Asp-297 residues play an important role in the protein−inhibitor interactions. These results might be useful to design compounds with more interesting inhibitory activity on the basis of its three-dimensional structure.