THEORETICAL STUDIES ON THE DYNAMIC ASPECTS OF MACROMOLECULAR FUNCTION

在本报告所述期间，出版了涉及下列项目的论文：(1)热波动势的反应动力学；(2)单分子多态构象动力学荧光理论；(3)蛋白质折叠的简单模型，说明了理解这一过程所需的大量概念，包括熵势垒、过渡态、漏斗和单指数折叠动力学的起源。第一篇论文讨论的是环境的波动，例如酶活性部位的波动，如何影响化学反应的速率。第二篇论文解决了一个问题，即人们应该如何解释最近和新的荧光实验，而不是对大量样品，而是对单个分子。第三篇论文介绍了捕获蛋白质折叠最基本方面的最简单模型，即熵（即构型的数量）和能量随着折叠的发生而减少。这与大多数化学反应相反，化学键首先被打破，导致能量增加。有趣的发现是，这个“骨架”模型能够解释数量惊人的实验趋势，表明这些结果是如何从最简单的物理假设中得出的。

In this reporting period, papers dealing with the following projects appeared in print: (1) Reaction dynamics on a thermally fluctuating potential; (2) Theory of the fluorescence of singlymolecules undergoing multistate conformational dynamics; (3) Asimple model for protein folding that illustrates a large numberof concepts needed to understand this process, including entropic barriers, transition states, funnels and the origin of single exponential folding kinetics. The first paper deals with the important problem of how fluctuations in the environment, such as those that occur in the active site of an enzyme, influence the rate of a chemical reaction. The second paper addresses the problem of how one should interpret recent and novel fluorescence experiments not on bulk samples but on individual molecules. The third paper introduces the simplest model that captures themost fundamental aspect of protein folding, namely that both the entropy (that is the number of configurations) and the energy decrease as folding occurs. This is in contrast to most chemical reactions where bonds are first broken, leading to an increase in energy. The interesting finding is that this "bare bones"model is able to account for a surprising number of experimental trends, showing how such results follow from the simplest physical assumptions.