title: The left-handed Z-DNA conformation in oligodeoxynucleotides containing different amounts of AT base pairs: a far UV circular dichroism study.
abstract: A number of fully self-complementary oligodeoxynucleotides have been synthesized and examined for their ability to assume the left-handed Z-DNA conformation in high salt solutions. The B- and Z-forms are identified by circular dichroism spectra, covering both the long- (220-300 nm) and short-wavelength (185-220 nm) regions, the latter showing CD bands very useful for identifying the sense of the helix winding. The main results of the study can be summarized as follows: a) sequences composed by AT and CG blocks do support the B to Z transition, even when the AT contents amounts to 50%; b) the occurrence of consecutive purine-purine or pyrimidine-pyrimidine dyads does not inhibit the B to Z transition, although a stronger reduction of water activity is required; c) (AC)n and (GT)n containing oligonucleotides do undergo the B to Z transition in solution; d) a millimolar quantity of Ni2+ concomitant with 5 M NaClO4 is found to be very effective in bringing about the B to Z transition in most of the sequences considered in this study.
authors.affiliation: Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, Italy.
authors.forename: L E
authors.initials: LE
authors.lastname: Xodo
authors.forename: G
authors.initials: G
authors.lastname: Manzini
authors.forename: F
authors.initials: F
authors.lastname: Quadrifoglio
authors.forename: N
authors.initials: N
authors.lastname: Yathindra
authors.forename: G A
authors.initials: GA
authors.lastname: van der Marel
authors.forename: J H
authors.initials: JH
authors.lastname: van Boom
mesh_terms: D000225:Adenine; D001482:Base Composition; D001483:Base Sequence; D002942:Circular Dichroism; D004247:DNA; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D013936:Thymidine
chemical_list: D009841:Oligonucleotides; D004247:DNA; D000225:Adenine; D013936:Thymidine