Study of Small Molecules Binding to Xanthine Oxidase

Abstract

In this project, we study the binding of small molecules to xanthine oxidase (XOD). The molecules have similar skeletal structure to that of the purine ring with different peripheral atoms or groups. We will present the binding results of 4-Amino-1H-pyrazolo[3,4-d] pyrimidine-6-ol (APP6O). We performed ligand-protein docking using the free Autodock software and carried out binding study in solution by Saturation Transferred Difference NMR technique. XOD is an enzyme found in the human serum and organs (e.g. lung, liver). The normal function of XOD is the oxidation of hypoxanthine to xanthine, then to uric acid. High activity of XOD can lead to the disease gout, which is caused by the buildup of high level of uric acid in the blood. Molecules that can bind to XOD are potential inhibitors, which could be developed as possible remedies for treating gout symptoms. The results of interactions between the docked molecule and side chain groups, and the affinity energies were evaluated compared to the known binding of uric acid and allopurinol to XOD. Both the computer docking results and NMR results showed that the APP6O molecule binds to XOD.