Perepelytsya S M, Volkov S N
Bogolyubov Institute for Theoretical Physics, NAS of Ukraine, 14-b Metrologichna St., 03680, Kiev, Ukraine.
Eur Phys J E Soft Matter. 2010 Feb;31(2):201-5. doi: 10.1140/epje/i2010-10566-6. Epub 2010 Feb 12.
The Raman intensities of counterion vibrations with respect to the phosphate groups of the double-helix backbone (ion-phosphate modes) in the low-frequency spectra (< 200 cm(-1)) of B -DNA with different alkali metal counterions have been calculated using the model for DNA conformational vibrations and the valence-optic approach. The results have showed that the spectra of DNA with heavy counterions (Rb(+) and Cs(+)) differ from the spectra of DNA with light counterions (Na(+) and K(+)). The calculated spectra of DNA with heavy counterions are characterized by intensive modes of ion-phosphate vibrations that form one united band near 115 cm(-1). Ion-phosphate modes in the spectra of DNA with light counterions are characterized by higher frequencies (near 180 cm(-1)) and much lower intensity. Our calculations explain why the modes of ion-phosphate vibrations are observed in Cs-DNA spectra rather than in Na-DNA. The determined sensitivity of the intensities of DNA low-frequency spectra to the counterion type proves the existence of the ion-phosphate modes.
利用DNA构象振动模型和价光学方法，计算了具有不同碱金属抗衡离子的B -DNA低频光谱（<200 cm(-1)）中，抗衡离子相对于双螺旋主链磷酸基团振动的拉曼强度（离子 - 磷酸模式）。结果表明，具有重抗衡离子（Rb(+)和Cs(+)）的DNA光谱与具有轻抗衡离子（Na(+)和K(+)）的DNA光谱不同。具有重抗衡离子的DNA计算光谱的特征是离子 - 磷酸振动的强模式，在115 cm(-1)附近形成一个统一的带。具有轻抗衡离子的DNA光谱中的离子 - 磷酸模式具有较高的频率（接近180 cm(-1)）和低得多的强度。我们的计算解释了为什么在Cs -DNA光谱中观察到离子 - 磷酸振动模式，而在Na -DNA中没有。确定的DNA低频光谱强度对抗衡离子类型的敏感性证明了离子 - 磷酸模式的存在。
