The tautomeric stability of violapterin (2,4,6-trihydroxypteridine) was studied in gas phase and aqueous solution by means of quantum mechanical calculations at MP2/6-31G(d) and B3LYP/6-311+G(2d,p) levels. Of 17 possible tautomers, two tautomers were identified as the most stable forms in gas phase and aqueous solution. Deprotonation of these two tautomeric forms to five possible anions in aqueous solution was studied using the B3LYP/6-311+G(2d,p) level of theory. Comparison of calculated pKa value for each of these anions with the available experimental pKa value determined the likely path by which a proton is removed from the neutral violapterin in aqueous solution during the action of xanthine oxidase on the molecule.

Theoretical study of violapterin in gas phase and aqueous solution

253rd National Meeting (2017)

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