Temperature dependence of vibrational spectra provides important information about the geometry and stability of nucleic acid segments. Even in cases of simple structural transitions between the folded and unfolded states, three types of spectral changes may occur – the actual structural transition, the influence of temperature change on the oligonucleotide in the folded state, and that in the unfolded state. In this work, the temperature dependences of UV resonance Raman spectroscopy (RRS) spectra excited at 244 and 257 nm were measured on two dodecadeoxynucleotides, duplex and hairpin. In both cases, the total base composition was the same, containing (in the folded state) a double‐strand section of guanine‐cytosine (GC) pairs and a central section of adenine‐thymine (AT) pairs forming a flexible part of the double helix in the duplex or the loop in the hairpin. Principal component analysis (PCA) showed that UV RRS spectrum, unlike non‐resonance RS, can reliably distinguish between the three types of temperature changes. Spectral images of the changes confirmed the B‐form double helix of GC sections in both the duplex and hairpin and different base positions in AT base sections. Additionally, minimal stacking interactions between the bases in the loop and other types of interactions of adenine with the bases of the stem in the hairpin were shown, and the main effects of heating in the folded state on the GC sections manifested weakening of stacking interactions. The results demonstrate UV RRS potential for studies of non‐canonical nucleic acid structures, providing properly analyzed and executed measurements of temperature dependence.

中文翻译：

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温度对DNA片段结构排列的影响的完全UV共振拉曼分析

振动光谱的温度依赖性提供了有关核酸片段的几何形状和稳定性的重要信息。即使在折叠状态和未折叠状态之间发生简单的结构转变的情况下，也可能会发生三种类型的光谱变化：实际的结构转变，温度变化对处于折叠状态的寡核苷酸和处于折叠状态的寡核苷酸的影响。在这项工作中，在两个十二烷氧基核苷酸（双链体和发夹）上测量了在244和257 nm激发的UV共振拉曼光谱（RRS）光谱的温度依赖性。在这两种情况下，总基础成分是相同的 包含（处于折叠状态的）鸟嘌呤-胞嘧啶（GC）对的双链部分和腺嘌呤-胸腺嘧啶（AT）对的中央部分，形成双链体中双螺旋的柔性部分或发夹中的环。主成分分析（PCA）表明，与非共振RS不同，UV RRS光谱可以可靠地区分三种类型的温度变化。变化的光谱图像证实了双链体和发夹中的GC区段的B型双螺旋以及AT基础区段中的不同基础位置。另外，显示了环中的碱基之间的最小堆叠相互作用以及发夹中的腺嘌呤与茎的碱基之间的其他类型的相互作用，并且折叠状态下加热对GC截面的主要影响显示出堆叠相互作用的减弱。