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Updated: Aug 19, 2026

Analyzing and Building Nucleic Acid Structures with 3DNA
Published on: April 26, 2013
Conformational junctions between left-handed DNA in (dA-dT)16 and contiguous B-DNA in a supercoiled plasmid contain
K Nejedlý1, D M Lilley, E Palecek
1Institute of Biophysics, Czechoslovak Academy of Sciences, Brno.
Abstract:
Alternating adenine-thymine sequences in supercoiled DNA may undergo a transition to the left-handed Z-conformation in the presence of Ni2+ ions and high Na+ concentrations [(1989) FEBS Lett. 243, 313-317]. In this work we have studied the junctions between B- and Z-conformations in a supercoiled plasmid containing a (dA-dT)16 insert, by means of chemical probing. We observed enhanced reactivity of bases at both ends of the alternating tract to chloro- and bromoacetaldehyde. The degree of chemical reactivity was found to increase with the level of negative supercoiling. Only individual bases were observed to be reactive in the B-Z junctions, consistent with tightly localized interfacial regions.
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