Vorlícková M, Sági J
Institute of Biophysics, Czechoslovak Academy of Sciences, Brno.
Nucleic Acids Res. 1991 May 11;19(9):2343-7. doi: 10.1093/nar/19.9.2343.
It is shown, using circular dichroism spectroscopy, that poly(dI-dC) is capable to isomerize into both Z-DNA and A-DNA in concentrated NaCl + NiCl2 and trifluoroethanol solutions, respectively. This polynucleotide also undergoes a cooperative, two-state transition in ethanol into a structure which most probably is a canonical B-DNA. This implies that the conformation of poly(dI-dC) is unusual in low-salt aqueous solution. The canonical B-DNA is also adopted by poly(dI-methyl5dC) in trifluoroethanol while this polynucleotide adopts Z-DNA not only in NaCl + NiCl2 but also in the presence of MgCl2. Poly(dI-methyl5dC) partially adopts X-DNA in concentrated CsF and mainly ethanolic solutions. Poly(dI-bromo5dC) isomerizes into Z-DNA not only in concentrated NaCl even in the absence of NiCl2 but also in concentrated MgCl2. This polynucleotide transforms between two distinct variants of Z-DNA in ethanol or trifluoroethanol solutions.
利用圆二色光谱表明,在浓NaCl + NiCl2溶液和三氟乙醇溶液中,聚(dI-dC)分别能够异构化为Z-DNA和A-DNA。这种多核苷酸在乙醇中也会发生协同的两态转变,形成一种很可能是标准B-DNA的结构。这意味着聚(dI-dC)在低盐水溶液中的构象是不寻常的。聚(dI-甲基5dC)在三氟乙醇中也采用标准B-DNA,而这种多核苷酸不仅在NaCl + NiCl2中,而且在MgCl2存在的情况下都采用Z-DNA。聚(dI-甲基5dC)在浓CsF和主要在乙醇溶液中部分采用X-DNA。聚(dI-溴5dC)不仅在浓NaCl中(即使没有NiCl2),而且在浓MgCl2中都异构化为Z-DNA。这种多核苷酸在乙醇或三氟乙醇溶液中在两种不同的Z-DNA变体之间转变。