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Role of tautomerism of 2-azaadenine and 2-azahypoxanthine in substrate recognition by xanthine oxidase

Posted June 8th, 2010 by pschmidtke
TitleRole of tautomerism of 2-azaadenine and 2-azahypoxanthine in substrate recognition by xanthine oxidase
Publication TypeJournal Article
Year of Publication1997
AuthorsHernandez, B, Orozco M, Luque FJ
JournalJournal of computer-aided molecular design
Volume11
Issue2
Pagination153 - 162
Date Published1997/03//
KeywordsAdenine/analogs & derivatives/chemistry; Binding Sites; Gases; Hypoxanthines/chemistry; Isomerism; Models, Molecular; Molecular Structure; Solutions; Substrate Specificity; Thermodynamics; Water; Xanthine Oxidase/chemistry/metabolism
AbstractThe tautomerism of 2-azaadenine and 2-hypoxanthine has been examined in the gas phase and in aqueous solution. The tautomerism in the gas phase has been studied by means of semiempirical and ab initio quantum-mechanical computations, as well as density-functional calculations. The influence of the aqueous solvent on the relative stability between tautomers has been estimated from self-consistent reaction field calculations performed with different high-level continuum models. The results provide a detailed picture of the tautomeric preference for these purine bases. The importance of tautomerism in the substrate recognition by xanthine oxidase is discussed. Finally, the rate of oxidation of 2-azaadenine and 2-hypoxanthine by xanthine oxidase is discussed in terms of the recognition model at the enzyme active site.