CD, absorption and thermodynamic analysis of repeating dinucleotide DNA, RNA and hybrid duplexes [d/r(AC)](12)center dot[d/r(GT/U)](12) and the influence of phosphorothioate substitution
CD, absorption and thermodynamic analysis of repeating dinucleotide DNA, RNA and hybrid duplexes [d/r(AC)](12)center dot[d/r(GT/U)](12) and the influence of phosphorothioate substitution
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DOI：
10.1093/nar/25.20.4098
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发表时间：
1997-10-15
影响因子：
14.9
通讯作者：
Gray, DM
中科院分区：
文献类型：
--
作者：
Clark, CL;Cecil, PK;Gray, DM
将含硫代磷酸酯键的5个双聚体的圆二色性（CD）光谱和熔融温度（T-m）数据与4个未修饰的双聚体的数据进行比较，以评估硫代磷酸酯修饰对DNA和DNA RNA双聚体结构和稳定性的影响。在0.15 M K+（磷酸盐缓冲液），pH 7.0中混合24 nt长的低聚物形成9个双聚体。未修饰的DNA DNA和RNA。以RNA双链作为参比b型和a型结构，修饰杂种S-d（AC）的CD谱图（12）。r(GU)（12）和r(AC)（12）。S-d(GT)（12）虽有差异，但与未修饰杂交种的光谱基本一致。双相化合物S-d（AC）的CD谱在性状上更偏向于a型而非b型（12）。d(GT)（12）和d(AC)（12）。S-d(GT)（12）与d(AC)（12）相似。d(GT)（12）中，除了长波长CD波段减少外，DNA双链上的硫修饰对其CD谱有明显的影响，热稳定性的顺序为：RNA。RNA b> dna。DNA b> DNA。RNA, dna。DNA b> s-dna。RNA b> s - dna。一条链的硫代磷酸化降低了7.8 +/- 0.6℃的熔化温度，无论取代是在杂交还是DNA双工中，热力学参数都是从热熔化曲线的多态分析中获得的。有趣的是，硫代磷酸化的不稳定效应似乎是由DNA形成时熵的差异引起的。DNA双链，而DNA的不稳定效应。RNA杂合体似乎来自于焓的不同。
Circular dichroism (CD) spectra and melting temperature (T-m) data for five duplexes containing phosphorothioate linkages were compared with data for four unmodified duplexes to assess the effect of phosphorothioate modification on the structure and stability of DNA DNA and DNA RNA duplexes, Nine duplexes were formed by mixing oligomers 24 nt long in 0.15 M K+ (phosphate buffer), pH 7.0. Unmodified DNA DNA and RNA.RNA duplexes were used as reference B-form and A-form structures, The CD spectra of the modified hybrids S-d(AC)(12).r(GU)(12) and r(AC)(12).S-d(GT)(12) differed from each other but were essentially the same as the spectra of the respective unmodified hybrids. They were more A-form than B-form in character, CD spectra of duplexes S-d(AC)(12).d(GT)(12) and d(AC)(12).S-d(GT)(12) were similar to that of d(AC)(12).d(GT)(12), except for a reduced long wavelength CD band, Sulfur modifications on both strands of the DNA duplex caused a pronounced effect on its CD spectrum, The order of thermal stability was: RNA.RNA > DNA.DNA > DNA.RNA, S-DNA.DNA > S-DNA.RNA > S-DNA.S-DNA. Phosphorothioation of one strand decreased the melting temperature by 7.8 +/- 0.6 degrees C, regardless of whether the substitution was in a hybrid or DNA duplex, Thermodynamic parameters were obtained from a multistate analysis of the thermal melting profiles, Interestingly, the destabilizing effect of the phosphorothioate substitution appears to arise from a difference in the entropy upon forming the DNA.DNA duplexes, while the destabilizing effect in the DNA.RNA hybrids appears to come from a difference in enthalpy.