A number of analogues of nucleic acid bases have been the target of extensive studies because of their importance in many biological studies. The oxygen of the bases is substituted with sulfur or selenium to produce an important class of analogues. 6-Selenoguanine (SeG) has a significant activity against L5178Y lymphoma cells. Information on the acid dissociation constants and the tautomerism of the molecules is required to provide a molecular level understanding of biological processes. Various tautomers of SeG were investigated using the B3LYP flavor of DFT in combination with the Poisson-Boltzmann continuum-solvation model. We show that the major tautomer of neutral SeG in aqueous solution is the amino-seleno form  with a minor contribution from other amino-seleno forms. The N7 site is the most suitable for protonation than other sites. The pKa1 value of SeG was 2.19, the pKa2 value was 7.77, and the pKa3 value was 11.35.

Density functional theoretical study on the pK<sub>a</sub> values of 6-selenolguanine

243rd National Meeting (2012)

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Density functional theoretical study on the pKa values of 6-selenolguanine

Density functional theoretical study on the pK_a values of 6-selenolguanine