Feuerstein B G, Marton L J, Keniry M A, Wade D L, Shafer R H
Nucleic Acids Res. 1985 Jun 11;13(11):4133-41. doi: 10.1093/nar/13.11.4133.
Spectroscopic studies on solutions of poly(dG-m5dC) over a wide range of salt concentration are presented. Low salt solutions [( Na+]) less than 2 mM) of poly(dG-m5dC) produce circular dichroism (CD) spectra typical of the left-handed, Z form at high salt [( Na+] = 1.75 M). Solutions of poly(dG-m5dC) at intermediate salt concentrations, e.g., 142 mM, yield CD spectra characteristic of the right-handed, B conformation. 31p NMR spectra of the low salt form of poly(dG-m5dC) reveal two well separated peaks, split by 1.4 ppm, consistent with a dinucleotide repeat. Kinetic studies show that the transition from the low salt form to teh right-handed B form is slow, as expected for a major conformational change. These results suggest that the Z conformation in poly(dG-m5dC) can be stabilized at very low salt as well as at high salt.
本文展示了在广泛盐浓度范围内对聚(dG-m5dC)溶液的光谱研究。低盐溶液[(Na +)小于2 mM]中的聚(dG-m5dC)在高盐[(Na +)= 1.75 M]时会产生典型的左旋Z型圆二色性(CD)光谱。中等盐浓度(例如142 mM)下的聚(dG-m5dC)溶液会产生右手B构象特征的CD光谱。聚(dG-m5dC)低盐形式的31P NMR光谱显示出两个分离良好的峰,分裂为1.4 ppm,这与二核苷酸重复一致。动力学研究表明,从低盐形式转变为右手B形式的过程很慢,这对于主要的构象变化来说是预期的。这些结果表明,聚(dG-m5dC)中的Z构象在非常低的盐浓度以及高盐浓度下都可以稳定存在。