Correlation of docking energies with spectroscopic kinetic assays of potential xanthine oxidase substrates

Abstract

Here we present a docking model that ranks compounds according to their potential effectiveness as a potential substrate or inhibitor. We utilize xanthine oxidase (XO), a multi-cofactor oxido-reductase which converts hypoxanthine to xanthine and xanthine to uric acid. During the reductive half reaction, electrons flow from the molybdopterin, to each of two Fe/S centers, and finally to FAD. During the oxidative half reaction, electrons are passed from the FAD to O 2 . Under ideal physiological conditions, this reduction of oxygen generates H 2 O 2 and, under multiple turnover conditions, superoxide in amounts which is regulated by catalase and superoxide dismutase. Utilizing computer modeling predictions of the docking orientations and energies of a group of purine based structures was selected. Correlating computer estimations with steady state kinetic data, a rapid screening process for inhibittor prediction was highlighted. This method allows educated selection of likely inhibitors, thereby decreasing the time and supplies required to complete a traditional kinetic analysis screening. Results demonstrate the functionality and reliability of this method and have proven particularly useful in understanding binding orienttations or poses of each compound.