The Left-Handed Z-DNA Conformation in Oligodeoxynucleotides Containing Different Amounts of AT Base Pairs: A Far UV Circular Dichroism Study |
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| Authors: | Luigi Emilio Xodo Giorgio Manzini Franco Quadrifoglio Narayanarao Yathindra Gijs A van der Marel Jacques H van Boom |
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| Institution: | 1. Department of Biochemistry, Biophysics and Macromolecular Chemistry , University of Trieste , I-34127 , Italy;2. Institute of Biology, Faculty of Medicine University of Udine , via Gervasutta 48, I-33100 , Udine , Italy;3. Department of Crystallography , Biophysics University of Madras , India;4. Gorlaeus Laboratories State University , P.O. Box 95022300, RA Leiden , The Netherlands |
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| Abstract: | 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 NaC104 is found to be very effective in bringing about the B to Z transition in most of the sequences considered in this study. |
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