title: A study of H-bonding of 3- and 5-substituted 6-aminouracils in duplex and triplex structures.
abstract: All possible dimers of the title modified bases with native nucleobases [10 dimers from 3-methylated 6-aminouracils (3sau) and 20 from 5-methyled 6-aminouracils (5sau), respectively have been calculated by ab initio method (Hartree-Fock method, 3 21G basis set). We have found two potential duplexes of 5sau and three possible duplexes of 3sau. Altogether seven dimers containing one or two bifurcating H-bonds have been found. Later on, five triplexes from ten possible calculated dimers have been found. In two of them the amino group of 6-aminouracil moiety takes part in H-bonding and there are H-bonds, too, between the first and third base of the triplexes causing an extra stabilization.
authors.affiliation: Department of Medicinal Chemistry, Hungarian Academy of Sciences, University of Szeged, Szeged, Hungary.
authors.forename: E
authors.initials: E
authors.lastname: Szájli
authors.forename: G
authors.initials: G
authors.lastname: Paragi
authors.forename: L
authors.initials: L
authors.lastname: Kovács
mesh_terms: D001482:Base Composition; D004247:DNA / Q000737:chemistry; D019281:Dimerization; D006860:Hydrogen Bonding; D008956:Models, Chemical; D008958:Models, Molecular; D008967:Molecular Biology / Q000379:methods*; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D009692:Nucleic Acid Heteroduplexes; D012984:Software; D014498:Uracil / Q000737:chemistry*
chemical_list: D009692:Nucleic Acid Heteroduplexes; D014498:Uracil; D004247:DNA