SUBUNIT STRUCTURE OF CHROMATIN

这项研究的基本目标是定量地了解 核小体中DNA-组蛋白核心相互作用的稳定性。 这将通过以下研究进行分析：（a）核小体滑动的动力学 （B）核小体的解离平衡。 解离 平衡将被解释的模型，其中包括 将组蛋白八聚体解离成六聚体、四聚体和二聚体， 组蛋白 沉降平衡将用于分析 组蛋白核心解离，以及沉降平衡， 沉降速度和凝胶电泳将用于 核小体解离研究。 组蛋白乙酰化的影响将 使用富含修饰的组蛋白的重构颗粒进行测定。 滑动过程将通过两种方式进行分析。 直接测量 在克隆的DNA上以分阶段的方式重组的组蛋白核心的滑动 片段将用于确定的基本机制和基本 滑动率 核小体解离的动力学（似乎 涉及滑动机制）将使用圆二色性进行研究 和/或新的电泳技术。 同样，组蛋白的影响 将研究修改费率。 有证据表明，核小体的稳定性和它们在 DNA可能在DNA复制、修复、 和转录。 因此，DNA-组蛋白定量分析 相互作用可能是至关重要的，以充分理解这些过程， 真核生物

The fundamental objective of this research is a quantitative understanding of the stability of the DNA-histone core interaction in the nucleosome. This will be analyzed by studies of (a) the kinetics of nucleosome sliding on DNA, and (b) the dissociation equilibria of nucleosomes. Dissociation equilibria will be interpreted in terms of a model which includes the dissociation of the histone octamer into hexamers, tetramers and dimers of the histones. Sedimentation equilibrium will be used to analyze the histone core dissociation, and a combination of sedimentation equilibrium, sedimentation velocity and gel electrophoresis will be employed for the nucleosome dissociation studies. The effects of histone acetylation will be assayed, using reconstituted particles enriched in modified histones. The sliding process will be analyzed in two ways. Direct measurement of sliding of a histone core reconstituted in a phased fashion on a cloned DNA fragment will be used to determine the fundamental mechanism and basic sliding rate. The kinetics of nucleosome dissociation (which seems to involve a sliding mechanism) will be studied using circular dichroism and/or a new electrophoretic technique. Again, the influence of histone modification on the rate will be studied. There is evidence that stability of nucleosomes and their displacement on DNA may be of major importance in such processes as DNA replication, repair and transcription. Therefore, a quantitative analysis of DNA-histone interactions may be vital to a full comprehension of these processes on eukaryots.