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Unique tautomeric and recognition properties of thioketothymines?

Posted June 8th, 2010 by pschmidtke
TitleUnique tautomeric and recognition properties of thioketothymines?
Publication TypeJournal Article
Year of Publication2009
AuthorsFaustino, I, Avino A, Marchan I, Luque FJ, Eritja R, Orozco M
JournalJournal of the American Chemical Society
Volume131
Issue35
Pagination12845 - 12853
Date Published2009/09/09/
KeywordsBase, DNA/chemistry/genetics;, Gases/chemistry;, Isomerism;, of, Pairing;, Reproducibility, Results;, Sequence;, Thermodynamics;, Thymine/chemistry;, Water/chemistry
AbstractThe tautomeric and recognition properties of thymine, 2- and 4-thioketothymines have been studied by means of accurate ab initio methods combined with molecular dynamics simulations and free energy calculations. In contrast to previous suggestions in the literature, the replacement of carbonyl oxygens by sulfur atoms does not lead to dramatic changes in tautomeric properties of the pyrimidine derivatives neither in vacuum nor in aqueous solution. Moreover, the presence of thioketothymines induces only mild changes in DNA structure, stability and fidelity. Despite the fact that mismatching can largely stabilize minor tautomeric forms, thioketothymines are found in the canonical thioketo-form irrespective of the paired base. Our theoretical results, confirmed by new experimental studies, describe the complete tautomeric and recognition characteristics of thioketothymines and demonstrate that both 2-thioketo and 4-thioketothymine are excellent molecules to introduce special chemical properties in modified DNA.