Fabriciová G, Miskovský P, Jancura D, Kocisová E, Lisý V
Biophysics Division, Faculty of Sciences, P. J. Safárik University, Kosice, Slovakia.
Gen Physiol Biophys. 1995 Jun;14(3):203-16.
Poly(dI-dC) in aqueous solution can undergo different equilibrium geometries which strongly depend on the salt nature and the concentration. These structures were studied by classical Raman spectroscopy (RS). Spectral changes depending on NaCl concentration and on the presence of Ni2+ ions were observed and interpreted on the basis of previously obtained results from resonance RS studies of poly(dI-dC) and classical RS studies for other alternating purine-pyrimidine polydeoxyribonucleotides, i.e. poly(dG-dC), poly(dA-dT) and poly(dA-dC)(dG-dT), which also showed B to Z conformational transitions upon varying the salt concentrations. It is shown that: i) The low-salt structure (0.1 mol/l NaCl) is in the pure canonical B conformation. ii) The high-salt (5 mol/l NaCl) Raman spectrum is similar to that obtained for the low-salt concentration. Thus the high-salt structure corresponds to the right-handed polymer with characteristic bands for both the B (predominant) and A conformations with some weak Z conformation markers which indicate a tendency for B to Z conformational transition of the polymer. iii) The addition of 9.10(-3) mol/l NiCl2 to the high-salt solution induces Z-conformation of the polymer.
水溶液中的聚（dI-dC）可呈现不同的平衡几何构型，这强烈依赖于盐的性质和浓度。这些结构通过经典拉曼光谱（RS）进行研究。观察到了取决于氯化钠浓度和镍离子存在情况的光谱变化，并根据先前对聚（dI-dC）的共振RS研究以及对其他交替嘌呤 - 嘧啶多脱氧核糖核苷酸（即聚（dG-dC）、聚（dA-dT）和聚（dA-dC）（dG-dT））的经典RS研究结果进行了解释，这些研究在改变盐浓度时也显示出从B构象到Z构象的转变。结果表明：i）低盐结构（0.1 mol/l氯化钠）处于纯经典B构象。ii）高盐（5 mol/l氯化钠）拉曼光谱与低盐浓度下获得的光谱相似。因此，高盐结构对应于具有B（主要）和A构象特征谱带的右手聚合物，带有一些弱的Z构象标记物，这表明聚合物有从B构象向Z构象转变的趋势。iii）向高盐溶液中添加9.10（-3）mol/l氯化镍会诱导聚合物形成Z构象。
