Krueger W C, Prairie M D
Physical and Analytical Chemistry, Upjohn Company, Kalamazoo, MI 49001.
Chem Biol Interact. 1991;79(2):137-49. doi: 10.1016/0009-2797(91)90078-l.
The calf thymus DNA (CT-DNA) and poly(dI-dC).poly(dI-dC) binding properties of the natural antitumor antibiotic CC-1065 and selected analogs of CC-1065 were studied by circular dichroism (CD) and absorbance methods. The results indicate that the intense long wavelength DNA-induced CD band of these molecules originates from a chiral electronic transition which is delocalized over the whole molecule. Both the covalently bound species (N-3 adenine adduct) and the reversibly bound species exhibit the characteristic spectral behavior of an inherently dissymmetric chromophore when these agents bind within the minor groove of B-form DNA. This mechanism of optical activity accounts for why CC-1065 shows a weak CD in buffer but a very intense induced CD at long wavelength when bound to DNA, why the intensity of the induced CD of CC-1065 analogs depends upon how many fused ring systems the analog contains, and why covalently bound analogs having the mirror image configuration of the natural configuration also exhibit an intense positive induced CD band at long wavelength.
通过圆二色性（CD）和吸光度方法研究了天然抗肿瘤抗生素CC - 1065及其选定类似物与小牛胸腺DNA（CT - DNA）和聚（dI - dC）.聚（dI - dC）的结合特性。结果表明，这些分子强烈的长波长DNA诱导的CD带源于一种在手性分子上离域的电子跃迁。当这些试剂结合在B型DNA的小沟内时，共价结合的物种（N - 3腺嘌呤加合物）和可逆结合的物种都表现出固有不对称发色团的特征光谱行为。这种光学活性机制解释了为什么CC - 1065在缓冲液中显示出较弱的CD，但与DNA结合时在长波长处显示出非常强烈的诱导CD，为什么CC - 1065类似物的诱导CD强度取决于类似物所含稠环系统的数量，以及为什么具有天然构型镜像构型的共价结合类似物在长波长处也显示出强烈的正诱导CD带。
