POLYAMINE-POLYNUCLEOTIDE INTERACTIONS

总的目标是了解DNA 中的更改折叠并形成有序聚合 离子条件。自始至终的目的都是为了了解 静电学、位点结合、水结构的重要性 新型DNA螺旋构型AS的调控和稳定 离子施加影响的方式。具体目标是 1.建立一致的统计热力学和动力学 解释环面尺寸惊人恒定的机理 以及棒状DNA颗粒被多胺和 六胺钴(III)，与DNA分子量无关， 通过激光光散射和电子显微镜进行测量。 2.对附近水域的模型进行计算机模拟 带电表面或极表面将检验这一想法的合理性 这些离子不仅通过静电作用，或者通过与特定的 也受它们对DNA附近水结构的影响 表面。 3.使用化学、抗体和光谱探针和螺旋- 线圈过渡理论检验自然冷凝的想法 DNA可能是形成和随后的结果 非B DNA区域的关联(如Z或P形式) 随机出现的嘌呤-嘧啶交替序列 残留物。 4.发展了DNA的聚合物统计热力学理论 由同时携带聚合物-聚合物的阴离子多肽坍塌 考虑不相容和离子聚合物膨胀，以及 进行光散射和沉淀实验，以 绘制相图以与理论相比较 期望值。 简单离子和离子聚合物对DNA的紧致作用 感兴趣的DNA包装在病毒颗粒和 染色质，并可能导致更好地理解物理 基因表达和DNA调控的机制 复制。

The overall goal is to understand the mechanisms whereby DNA collapses and forms ordered aggregates in response to changes in ionic conditions. The aim throughout is to understand the relative importance of electrostatics, site binding, water structure modulation, and stabilization of novel DNA helix geometries as ways in which ions exert their influence. Specific aims are to 1. Develop a consistent statistical thermodynamic and kinetic mechanism that explains the striking constancy os size of toroidal and rodlike DNA particles collapsed by polyamines and hexammine cobalt(III), independent of the DNA molecular weight, as measured by laser light scattering and electron microscopy. 2. Perform computer simulations on models of water near charged or polar surfaces that will test the plausibility of the idea that ions act not only electrostatically or by binding to specific sites, but also by their effects on water structure near DNA surfaces. 3. Use chemical, antibody, and spectroscopic probes and helix- coil transition theory to test the idea that condensation of natural DNA may be the result of the formation and subsequent association of regions of non-B DNA (e.g. Z or P form) in randomly occurring sequences of alternating purine-pyrimidine residues. 4. Develop a polymer statistical thermodynamic theory of DNA collapse by anionic polypeptides that takes both polymer-polymer incompatibility and ionic polymer expansion into account, and perform light scattering and sedimentation experiments that will map out a phase diagram to compare with theoretical expectations. Compaction of DNA by simple ions and ionic polymers is of interest as a model for DNA packaging in virus particles and chromatin, and may lead to better understanding of the physical mechanisms underlying regulation of gene expression and DNA replication.