title: Unusual conformation of (dA)n.(dT)n-tracts as revealed by cyclobutane thymine-thymine dimer formation.
abstract: Cyclobutane dimer formation has been used to probe conformation of (dA)n.(dT)n-tracts cloned in plasmid DNA. The observed dimer probability patterns for (dA)n.(dT)n-tracts with n greater than or equal to 4 exhibit maximum intensity at the 3'-terminal TT site of Tn-tract, whereas photoreactivity at all the other TT sites is inhibited. Both the temperature and dimethyl sulfoxide increase dimer formation within Tn-tracts and result in an even dimer pattern. The data obtained have been interpreted in terms of an unusual structure adopted by (dA)n.(dT)n-tracts. An influence of flanking base pairs, ethidium bromide binding and ionic strength has also been studied.
authors.affiliation: Institute of Molecular Genetics, USSR Academy of Sciences, Moscow.
authors.forename: V
authors.initials: V
authors.lastname: Lyamichev
mesh_terms: D001483:Base Sequence; D003503:Cyclobutanes / Q000737:chemistry*; D004121:Dimethyl Sulfoxide / Q000737:chemistry; D004996:Ethidium / Q000737:chemistry; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010957:Plasmids / Q000235:genetics; D011067:Poly dA-dT / Q000737:chemistry* / Q000528:radiation effects; D011740:Pyrimidine Dimers / Q000737:chemistry*; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D003503:Cyclobutanes; D011740:Pyrimidine Dimers; D011067:Poly dA-dT; D004996:Ethidium; D004121:Dimethyl Sulfoxide