title: T-T base mismatches enhance drug binding at the branch site in a four-arm DNA junction.
abstract: Base mismatches--non Watson-Crick pairing between bases--can arise in duplex DNA as a consequence of mutational events or by recombination. In a duplex, the sequence of the two bases involved, and those flanking the site of mismatch, determines the local structure and extent of destabilization of the helix. Base mismatches can arise also in recombination of nonhomologous strands, and their occurrence in Holliday recombination intermediates can influence the outcome of general or specialized recombination events. We have previously reported that the branch site in a DNA junction can interact selectively with a variety of ligands. Here we describe the thermodynamics of junctions containing T-T mismatches flanking the branch and show that these structures bind methidium and other intercalators with higher affinity than junctions lacking mismatches.
authors.affiliation: Department of Chemistry, New York University, New York 10003.
authors.forename: M
authors.initials: M
authors.lastname: Zhong
authors.forename: M S
authors.initials: MS
authors.lastname: Rashes
authors.forename: L A
authors.initials: LA
authors.lastname: Marky
authors.forename: N R
authors.initials: NR
authors.lastname: Kallenbach
mesh_terms: D001482:Base Composition; D001483:Base Sequence; D001665:Binding Sites; D002152:Calorimetry, Differential Scanning; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004047:Diethyl Pyrocarbonate / Q000494:pharmacology; D007364:Intercalating Agents / Q000378:metabolism; D008969:Molecular Sequence Data; D009993:Osmium Tetroxide / Q000494:pharmacology; D013816:Thermodynamics; D013936:Thymidine / Q000737:chemistry*
chemical_list: D007364:Intercalating Agents; D004247:DNA; D004047:Diethyl Pyrocarbonate; D009993:Osmium Tetroxide; D013936:Thymidine