title: Unique tautomeric and recognition properties of thioketothymines?
abstract: The 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.
authors.affiliation: Joint IRB-BSC Program on Computational Biology, Parc Científic de Barcelona, Josep Samitier 1-5, Barcelona 08028, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Faustino
authors.forename: Anna
authors.initials: A
authors.lastname: Aviño
authors.forename: Ivan
authors.initials: I
authors.lastname: Marchán
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Luque
authors.forename: Ramon
authors.initials: R
authors.lastname: Eritja
authors.forename: Modesto
authors.initials: M
authors.lastname: Orozco
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D004247:DNA / Q000737:chemistry / Q000235:genetics; D005740:Gases / Q000737:chemistry; D007536:Isomerism; D015203:Reproducibility of Results; D013816:Thermodynamics; D013941:Thymine / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D005740:Gases; D014867:Water; D004247:DNA; D013941:Thymine