SPECIFICITY OF INTERCALATION REACTIONS

各种各样的化合物通过嵌入与DNA结合。 而 这些嵌入剂对DNA的平均亲和力是相似的，不是所有的 嵌入剂在癌症治疗中是有效的。 分子 这种行为的依据是寻找。 是什么使嵌入化合物 有效的抗癌药物？ 我的假设是有效的嵌入剂 在癌症化疗中，认识到DNA在增殖中的一些特征， 细胞，不太有效的嵌入剂没有，无论是特定的DNA 构象或序列。 抗癌药物柔红霉素的前期工作 表明，一个可能的区别特征是能够 区分“游离”DNA和构造成核小体的DNA。 拟议 研究将从三个方面探索核小体作为药物受体。 首先，各种各样的嵌入剂与“游离”DNA的结合以及与 将研究核小体，看看临床有效的化合物是否 显示出类似于柔红霉素的辨别行为。 二、停流 和温度跳跃研究将用于开发合理的反应 乙锭和道诺霉素与核小体结合的机制。 最后，将进行光化学交联实验， 定位核小体DNA内的药物结合位点，以便 确定所有可能的嵌入位点是否可自由接近。 中 所提出的研究的另一个方面， 蒽环类抗生素广泛应用于癌症化疗， 探索使用光化学交联，现代“足迹” 技术和亲和层析。 最后，影响 将研究插层剂对B到Z过渡的影响，以确定其作用 嵌入剂作为DNA构象变化的变构效应物。 从这些研究中获得的信息将增强我们的基础 了解一类重要的配体-DNA相互作用，并应 为合理设计新的化疗药物提供依据 具有更高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.