一种在低盐条件下能诱导聚（dA-dT）发生独特构象变化的聚阳离子胺。
A polycationic amine that induces unique conformational changes in poly(dA-dT) in low salt.
作者信息
Zarlenga D S, Halsall H B, Day R A
出版信息
Nucleic Acids Res. 1984 Aug 10;12(15):6325-35. doi: 10.1093/nar/12.15.6325.
Circular dichroism was used to examine alterations in the secondary structure of poly(dA-dT) X poly(dA-dT) upon binding polymer X, a polycationic CD probe for aspects of DNA structure. Stable complex formation is evidenced by increasing Tm and the appearance of large extrinsic bands in the greater than 300 nm, region which increase proportionally with r (ratio of polymer charge to DNa phosphate), in the range 0.0 to 0.32. At relatively low values of r (less than .32), CD spectra of the poly(dA-dT) X poly(dA-dT)-polymer X complex show a gradual non-cooperative inversion in the long wavelength portion (275 nm) of the intrinsic band in low salt solutions suggesting structural and conformational flexibility in poly(dA-dT) X poly(dA-dT) and further implicating polymer X as a potential probe for variations in DNA secondary structure. The dinucleotide repeat configuration of poly(dA-dT) X poly(dA-dT) is presumed to play a role in the observed intrinsic CD changes. NMR data support an "alternating B" conformation for the complex.
利用圆二色性来检测聚（dA-dT）×聚（dA-dT）与聚合物X（一种用于研究DNA结构的聚阳离子型圆二色性探针）结合后二级结构的变化。Tm升高以及在大于300nm区域出现较大的外源带，这表明形成了稳定的复合物，在0.0至0.32范围内，这些外源带与r（聚合物电荷与DNA磷酸基团的比率）成比例增加。在相对较低的r值（小于0.32）时，聚（dA-dT）×聚（dA-dT）-聚合物X复合物的圆二色光谱在低盐溶液中显示出在本征带长波长部分（275nm）逐渐发生非协同反转，这表明聚（dA-dT）×聚（dA-dT）具有结构和构象灵活性，进一步表明聚合物X是检测DNA二级结构变化的潜在探针。聚（dA-dT）×聚（dA-dT）的二核苷酸重复构型被认为在观察到的本征圆二色性变化中起作用。核磁共振数据支持该复合物的“交替B”构象。
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