SPECIFICITY OF INTERCALATION REACTIONS

各种各样的化合物以插层方式与DNA结合。而当 这些嵌入剂对DNA的平均亲和力是相似的，并不都是 嵌入剂在治疗癌症方面是有效的。分子 寻找这一行为的依据。是什么让插层化合物成为 有效的抗癌药物？我的假设是嵌入器是有效的 在癌症化疗中识别DNA在增殖过程中的某些特征 效率较低的嵌入剂做不到的细胞，或者是特定的DNA 构象或序列。抗癌药物柔红霉素的研究进展 表明一个可能的区别特征是有能力 区分“游离”DNA和结构成核小体的DNA。建议数 研究将从三个方面探索核小体作为药物受体的作用。 首先，各种各样的嵌入剂与DNA和TO结合 将对核小体进行研究，看看临床上有效的化合物是否 表现出类似柔红霉素的辨别行为。第二，停流 温度跳跃研究将被用来开发合理的反应 乙锭和柔红霉素与核小体结合的机制。 最后，将进行光化学交联实验，以 在核小体DNA中定位药物结合部位，以便 确定是否所有可能的夹层位置都可以自由访问。在一个 拟议研究的不同方面，序列特异性 在癌症化疗中广泛使用的蒽环类抗生素，将 探索使用光化学交联剂，现代“足迹” 技术和亲和层析。最后， 将研究嵌入剂对B到Z转变的影响，以确定其作用 作为DNA构象变化的变构效应的嵌入物。 从这些研究中获得的信息将增强我们的基础 理解一类重要的配体-DNA相互作用，并应 为合理设计新型化疗药物提供依据 具有更强的特异性和效力的化合物。

A wide variety of compounds bind to DNA by intercalation. While the average affinity of these intercalators for DNA is similar, not all intercalators are effective in the treatment of cancer. The molecular basis for this behavior is sought. What makes an intercalating compound an effective cancer drug? My hypothesis is that the intercalators effective in cancer chemotherapy recognize some feature of the DNA in proliferating cells that the less effective intercalators do not, either a particular DNA conformation or sequence. Previous work on the cancer drug daunomycin indicated that one possible distinguishing trait is the ability to discriminate "free" DNA from DNA structured into nucleosomes. The proposed research will explore the nucleosome as a drug receptor in three ways. First, the binding of a wide variety of intercalators to "free" DNA and to nucleosomes will be studied, to see if the clinically effective compounds show discriminating behavior analogous to daunomycin. Second, stopped-flow and temperature-jump studies will be used to develop plausible reaction mechanisms for the binding of ethidium and daunomycin to nucleosomes. Finally, photochemical crosslinking experiments will be performed to localize drug binding sites within the nucleosomal DNA, in order to establish if all possible intercalation sites are freely accessible. In a separate aspect of the proposed research, the sequence specificity of anthracycline antibiotics widely used in cancer chemotherapy, will be explored using photochemical crosslinking, modern "footprinting" techniques, and affinity chromatography. Finally, the influence of intercalators on the B to Z transition will be studied, to define the role of intercalators as allosteric effectors of DNA conformational changes. The information obtained from these studies will enhances our fundamental understanding of an important class of ligand-DNA interactions, and should provide a foundation for the rational design of new chemotherapeutic compounds of greater specificity and potency.