Conformational junctions between left‐handed DNA in (dA‐dT)16 and contiguous B‐DNA in a supercoiled plasmid contain chemically reactive bases

FEBS Letters

Lilley, D.M.J.¹  Nejedlý, K.²  Paleček, E.² 

[1] Department of Biochemistry, The University, Dundee DD1 4HN, UK;Institute of Biophysics, Czechoslovak Academy of Sciences, Královopolská 135, 612 65 Brno, Czechoslovakia

关键词: Supercoiled DNA;    Left-handed (dA-dT)16;    B-Z junction;    Unpaired bases;    Chemical probe;    Bromoacetaldehyde;    Chloroacetaldehyde;    BAA;    bromoacetaldehyde;    CAA;    Chloroacetaldehyde;    DEPC;    diethyl pyrocarbonate.;   

DOI  :  10.1016/0014-5793(93)81178-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown