经致癌物N-甲基-4-氨基偶氮苯或4-氨基联苯修饰的聚（dG-dC）的圆二色性
Circular dichroism of poly(dG-dC) modified by the carcinogens N-methyl-4-aminoazobenzene or 4-aminobiphenyl.
作者信息
Abuaf P A, Kadlubar F F, Grunberger D
机构信息
Institute of Cancer Research/Comprehensive Cancer Center, College of Physicians and Surgeons, Columbia University, New York, NY 10032.
出版信息
Nucleic Acids Res. 1987 Sep 11;15(17):7125-36. doi: 10.1093/nar/15.17.7125.
Poly(dG-dC) was modified to different extents by the carcinogens 4-aminobiphenyl (ABP) or N-methyl-4-aminoazobenzene (MAB). HPLC analysis of the enzymatically hydrolyzed modified polymers indicates that more than 90% of the ABP and 81% of the MAB modification occurs at the C8 position of guanine. The conformational changes of the unmodified and modified polymers were studied as a function of ethanol and magnesium ion concentrations by the use of circular dichroism (CD). The modified polymers show a CD inversion pattern similar to that of the salt-induced B to Z transition of poly(dG-dC). Both of the modified polymers require less salt or ethanol than the unmodified polymer for the inversion of the spectra. The amount of ethanol or magnesium needed to induce the inverted CD spectrum is inversely proportional to the percentage of bound ABP or MAB. These data indicate that ABP and MAB can enhance conversion from B to Z conformation in alternating purine-pyrimidine sequences.
多聚（dG-dC）被致癌物4-氨基联苯（ABP）或N-甲基-4-氨基偶氮苯（MAB）不同程度地修饰。对经酶水解的修饰聚合物进行的高效液相色谱分析表明，超过90%的ABP修饰和81%的MAB修饰发生在鸟嘌呤的C8位。通过圆二色性（CD）研究了未修饰和修饰聚合物的构象变化与乙醇和镁离子浓度的关系。修饰后的聚合物呈现出与盐诱导的多聚（dG-dC）从B型向Z型转变相似的CD反转模式。与未修饰的聚合物相比，两种修饰后的聚合物在光谱反转时所需的盐或乙醇更少。诱导CD光谱反转所需的乙醇或镁的量与结合的ABP或MAB的百分比成反比。这些数据表明，ABP和MAB可以增强交替嘌呤-嘧啶序列中从B型向Z型构象的转变。
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