title: Peculiarities of the B to A transition of the lambda phage regulatory site OR3 and of its fragment.
abstract: Conformations of the synthetic deoxyoligonucleotide 17 base pairs long, which is an OR3 operator of lambda phage, and of its 9-b.p. fragment were studied by the circular dichroism method (CD). The regions of stability of the double-stranded state were determined for these duplexes. A comparison of the CD spectra for these oligonucleotides with the CD for a lengthy DNA showed the conformation of these short DNA pieces to belong to the B-family. A cooperative change in the CD spectra is observed in trifluoroethanol (TFE) solutions at a TFE concentration specific for each oligonucleotide, which is supposed to stem from a B to A transition. The length of the fragment was found to affect the ability for the B-A transition. The transition into the A form is hindered by 13% TFE for the short 9-nucleotide in comparison with the 17-nucleotide. We suggest that this is due to the B form stabilization by terminal base pairs (B-phility of the ends).
authors.affiliation: Institute of Molecular Biology, USSR Academy of Sciences, Moscow.
authors.forename: V I
authors.initials: VI
authors.lastname: Ivanov
authors.forename: L E
authors.initials: LE
authors.lastname: Minchenkova
authors.forename: A K
authors.initials: AK
authors.lastname: Schyolkina
authors.forename: B K
authors.initials: BK
authors.lastname: Chernov
authors.forename: A P
authors.initials: AP
authors.lastname: Yartsev
authors.forename: M P
authors.initials: MP
authors.lastname: Kirpichnikov
mesh_terms: D010582:Bacteriophage lambda / Q000235:genetics; D001483:Base Sequence; D002942:Circular Dichroism; D004279:DNA, Viral; D009690:Nucleic Acid Conformation; D009875:Operator Regions, Genetic; D013816:Thermodynamics; D014270:Trifluoroethanol
chemical_list: D004279:DNA, Viral; D014270:Trifluoroethanol