INFLUENCES OF MACROMOLECULAR CROWDING ON BIOCHEMICAL SYSTEMS

细胞内高浓度的大分子导致大的 排除的数量，可能会导致非常大的变化率， 涉及其他大分子的反应平衡。 以前的研究 我们自己和其他人对DNA的这种大分子拥挤效应 一直局限于模型系统的实证研究，留下未回答的问题， 关于拥挤环境下DNA功能的基本问题。 我们有 回答了其中的两个问题。 首先，我们研究了DNA和相关材料的有效体积， 拥挤的相互作用 两相体积分布法 前面描述的占用率用于确定 一系列小的双链和单链的拥挤相互作用 DNA片段 他们的行为完全符合一种简单的 理论处理，有效体积模型，用于预测 排除体积效应。 这些结果在《生物聚合物》杂志上发表。 其次，我们目前正在测量实际细胞的拥挤效应， 材料，E.大肠杆菌，在DNA测试系统上。 的 测试系统测量限制性组织的体外内聚率 λ DNA片段。 初步结果显示， 至少1-2个数量级。 除了这些实验研究，我正在写一篇关于 大分子拥挤与艾伦明顿（也是 NIDDKD）为1992年版的《生物物理学年度评论》和 生物物理结构

The high concentrations of macromolecules within cells result in large excluded volumes, potentially causing very large shifts in rates and equilibria of reactions involving other macromolecules. Prior studies of such macromolecular crowding effects on DNA by ourselves and others have been restricted to empirical studies of model systems, leaving unanswered basic questions about DNA function under crowded conditions. We have addressed two of those questions. First we have studied the effective volume of DNA and related materials in crowding interactions. The two-phase distribution assay for volume occupancy described earlier was used to determine the effective volumes in crowding interactions of a series of small double- and single-stranded pieces of DNA. Their behavior is fully consistent with a simple theoretical treatment, the available volume model, used for predicting excluded volume effects. These results are "in press" in Biopolymers. Second, we are currently measuring the crowding effects of actual cellular material, cytoplasmic extracts from E. coli, on a DNA test system. The test system measures the rate of in vitro cohesion of restriction fragments of lambda DNA. Preliminary results indicate accelerations of at least 1-2 orders of magnitude. In addition to these experimental studies, I am writing a review on macromolecular crowding in collaboration with Allen Minton (also of NIDDKD) for the 1992 edition of Annual Reviews of Biophysics and Biophysical Structure.