CIRCULAR DIFFERENTIAL SCATTERING AND CIRCULAR DIFFERENTIAL ABSORPTION OF DNA-PROTEIN CONDENSATES AND OF DYES BOUND TO DNA-PROTEIN CONDENSATES
CIRCULAR DIFFERENTIAL SCATTERING AND CIRCULAR DIFFERENTIAL ABSORPTION OF DNA-PROTEIN CONDENSATES AND OF DYES BOUND TO DNA-PROTEIN CONDENSATES
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DOI：
10.1021/bi00372a004
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发表时间：
1986-12-02
期刊：
影响因子：
2.9
通讯作者：
TINOCO, I
中科院分区：
文献类型：
--
作者：
PHILLIPS, CL;MICKOLS, WE;TINOCO, I
提供正和负 psi 型圆二色性 (CD) 光谱的 DNA-蛋白质缩合物（. psi 缩合物）结合嵌入和非嵌入染料。 CD 取决于圆形微分散射和圆形微分吸收；散射校正 CD 测量是圆形微分吸收的近似值。在 .psi 的 DNA 吸收带中观察到的圆形差分散射校正 CD 图案。在与 .psi 结合的嵌入剂的诱导 CD 带中模拟了缩合物。凝结物。凹槽结合染料 Hoechst 33342 与 .psi 结合的诱导散射校正 CD 和圆形微分散射图案。凝聚体与插入染料所看到的图案相反，而凹槽结合染料锰(III)内消旋四(4-N-甲基吡啶基)卟啉[MnIIITMpyP-4]没有表现出明显的诱导CD图案。大的圆形差分散射和散射校正的 CD 带被解释为由长程手性堆积产生，而不是近邻短程相互作用。染料插入 .psi 的 DNA 中。凝聚体具有与 DNA 碱基相同类型的长程手性堆积。因此，当染料插入到.psi的DNA中时，在可见光谱中也观察到源于DNA碱基的长程堆积的UV光谱中看到的.psi.型CD光谱。凝结物。我们的解释来自于观察到染料与 .psi 结合引起的圆形微分散射和圆形微分吸收。凝聚态仅取决于 .psi 的圆形微分吸收的符号和圆形微分散射的图案。没有结合染料的缩合物。两种凹槽结合染料诱导的 CD 模式的变化归因于微小但显着的结合角变化。来自与未缩合 DNA 结合的染料的传统 CD 信号因不同染料而异，并且没有显示出特定的趋势。小牛胸腺DNA与聚(赖氨酸-丙氨酸)和聚赖氨酸的缩合分别产生正和负ψ型CD谱。本研究中使用了五种嵌入染料和两种结合在 DNA 小沟中的染料：乙锭、丙黄素、H2TMpyP-4、Cu11TMpyP-4 和 NiIIITMpyP-4（嵌入染料）； MnIIITMpyP-4 和 Hoechst 33342（结合在 DNA 小沟中）。
DNA-protein condensates that give positive and negative .psi.-type circular dichroism (CD) spectra (.psi. condensates) bind intercalative and nonintercalative dyes. CD depends both on circular differential scattering and on circular differential absorption; scattering-corrected CD measurements are approximations to circular differential absorption. The circular differential scattering-corrected CD patterns observed in the DNA absorption band of .psi. condensates are mimicked in the induced CD band of intercalators bound to .psi. condensates. The induced scattering-corrected CD and circular differential scattering patterns of the groove-binding dye Hoechst 33342 bound to .psi. condensates are the inverse of the patterns seen with intercalative dyes, whereas the groove-binding dye manganese(III)meso-tetrakis(4-N-methylpyridyl)porphine [MnIIITMpyP-4] shows no significant induced CD patterns. The large circular differential scattering and scattering-corrected CD bands are interpreted as resulting from long-range chiral packing, rather than near-neighbor short-range interactions. Dyes intercalated into the DNA of the .psi. condensates have the same type of long-range chiral packing as the DNA bases. Therefore, the .psi.-type CD spectra seen in the UV spectra originating from the long-range packing of the DNA bases are also observed in the visible spectra when dyes are intercalated in the DNA of the .psi. condensates. Our interpretation comes from the observation that the induced circular differential scattering and circular differential absorption of the dye boundto the .psi. condensates depend only upon the sign of the circular differential absorption and the pattern of the circular differential scattering of the .psi. condensates without bound dye. The variation in the induced CD patterns of the two groove-binding dyes is attributed to small but significant binding angle changes. Conventional CD signals from dyes bound to uncondensed DNA vary for different dyes and show no particular trends. Condensation of calf thymus DNA with poly(lysine-alanine) and polylysine produced positive and negative .psi.-type CD spectra, respectively. Five intercalative dyes and two dyes that bind in the minor groove of DNAwere used in this investigation: ethidium, proflavin, H2TMpyP-4, Cu11TMpyP-4, and NiIITMpyP-4 (intercalative dyes); MnIIITMpyP-4 and Hoechst 33342 (bind in the DNA minor groove).