Fabriciova G, Miskovsky P, Jancura D, Lisy V
Department of Biophysics, P.J. Safarik University, Kosice, Slovakia.
J Biomol Struct Dyn. 1998 Oct;16(2):281-8. doi: 10.1080/07391102.1998.10508246.
Poly(dI-dC) in H2O and D2O solution can undergo different equilibrium geometries which strongly depend on the salt nature and concentration. These structures were studied by classical Raman spectroscopy in order to monitor a hydrogen-deuterium exchange kinetics in 8-CH group in inosine. Spectral and isotopic exchange rate changes depending on NaCl concentration were observed and interpreted on the basis of previously obtained results from resonance and classical Raman spectroscopy studies of poly(dI-dC) and hydrogen-deuterium exchange measurements of different conformations of nucleic acids. It is shown that: i) the Raman spectrum of low-salt poly(dI-dC) corresponds to the right-handed polymer with characteristic bands for B conformation, but the value of the retardation factor of isotopic exchange suggests that this form is not a pure canonical B form and that it contains some portion of the A form, ii) the Raman spectrum of the high-salt poly(dI-dC) corresponds to the right-handed polymer with characteristic bands for both the A and B conformations, iii) the retardation factor of hydrogen deuterium exchange for the high-salt form of poly(dI-dC) is essentially higher than in the low-salt form which indicates a dominant presence of the A form in the high-salt conformation of poly(dI-dC). This leads to the conclusion that the high-salt conformation of poly(dI-dC) is a mixture of A and B forms with the predominant A form.
聚（dI-dC）在水和重水溶液中会呈现不同的平衡几何结构，这强烈依赖于盐的性质和浓度。通过经典拉曼光谱对这些结构进行了研究，以便监测肌苷中8位-CH基团的氢-氘交换动力学。观察到了光谱和同位素交换速率随氯化钠浓度的变化，并根据先前从聚（dI-dC）的共振和经典拉曼光谱研究以及不同核酸构象的氢-氘交换测量中获得的结果进行了解释。结果表明：i）低盐聚（dI-dC）的拉曼光谱对应于具有B构象特征谱带的右手聚合物，但同位素交换延迟因子的值表明这种形式不是纯的标准B形式，并且它包含一部分A形式；ii）高盐聚（dI-dC）的拉曼光谱对应于具有A和B构象特征谱带的右手聚合物；iii）聚（dI-dC）高盐形式的氢-氘交换延迟因子基本上高于低盐形式，这表明在聚（dI-dC）的高盐构象中A形式占主导。由此得出结论，聚（dI-dC）的高盐构象是A和B形式的混合物，其中A形式占主导。
