STUDIES OF PROTEIN FOLDING PROBLEM

这个项目的一个长期目标是找到一种方法来预测三个- 根据氨基酸序列确定蛋白质的空间结构。 近年来和今年，我们取得了几项重要发现，其中包括 在本节中统一了所有以前关于蛋白质折叠的研究。二 包含大量数据的手稿已经由A.Fisher和 今年是H.Taniuchi。在以下方面，调查结果和原则 对这些手稿中所写的内容进行了总结。 大量的4个不同的同源和杂交的2-片段复合体 类型由适当的血红素和脱脂蛋白或脱脂蛋白制备 马、金枪鱼、酵母菌iso-1和念珠菌细胞色素c。 以结构、稳定性和结合的吉布斯能量变化为特征。 结果允许我们分配4个折叠单元，它们共同 代表细胞色素c折叠。单元1可自行折叠并由 本质上是右通道疏水核心和部分血红素。R.E. Dickerson和他的同事已经发现COOH末端螺旋接触 与NH2-末端螺旋形成右通道。2、3和4单元， 分别分配给左侧和右侧的核心以及 亚铁血红素的底部。 基于折叠单元-单元相互作用的证据，我们提出 真核细胞色素c以两种不同的方式折叠，这取决于 细胞色素作用下血红素与载脂蛋白结合后的温度 C合成酶：单元1-3-2-4或1-2-3-4.吉布斯能量变化 结合被发现根据不同种类的血红素片段结合而不同。 与哪种脱脂蛋白或脱脂蛋白。这一点更加明显 从不太有序的复合体到更有序的复合体。有证据表明 含铁-S络合物的这种吉布斯能变差 键主要是由于折叠单元-单元相互作用的扰动， 这可以通过联系核心群体来进行调解。在此基础上，一个自我 解释这种吉布斯能量的一组一致的残基取代 已分配差值。基于Gibbs能量变化差分的分析 在这项任务上提出了一个核心群体互动网络 可以将折叠单元芯从单元1扩展为折叠 进步了。这种额外的核心相互作用的模型，核心环路 提出了驱动折叠的相互作用/核心环合并。

A long range goal of this project is to find a way to predict the three- dimensional structure of proteins on the basis of the amino acid sequences. In recent years and this year, we have made several key findings which have unified all previous studies of protein folding in this Section. Two manuscripts containing a mass of data have been completed by A. Fisher and H. Taniuchi in this year. In the following the findings and principles written in these manuscripts are summarized. A large number of homologous and hybrid 2-fragment complex of 4 different types were prepared from appropriate heme and apofragments or apoproteins of horse, tuna, yeast iso-1 and Candida cytochromes c. The complexes were characterized for structure, stability and Gibbs energy change for binding. The results have allowed us to assign 4 folding units which collectively represents cytochrome c folding. Unit 1 folds by itself and consists essentially of the right channel hydrophobic core and a part of heme. R.E. Dickerson and colleagues have found that the COOH-terminal helix contacts with the NH2-terminal helix to form a right channel. Units 2, 3 and 4, respectively are assigned to the cores on the left and right sides and at the bottom of heme. Based on evidence of the folding unit - unit interaction we propose that eukaryotic cytochrome c folds in two alternative ways depending on the temperature after attachment of heme to apoprotein by action of cytochrome c synthetase: Unit 1->3->2->4 or 1->2->3->4. Gibbs energy change for binding was found to vary depending on which species of heme fragment binds with which species of apofragment or apoprotein. This is more pronounced going from the less ordered complex to the more ordered. Evidence suggests that such Gibbs energy change difference of complexes containing the Fe-S bond is mainly due to perturbation of the folding unit-unit interaction, which may be mediated by contacting core groups. Based on this, a self- consistent set of residue substitutions to account for this Gibbs energy difference is assigned. Analysis of Gibbs energy change difference based on this assignment has suggested that a network of core group interaction may expand throughout the folding unit cores from Unit 1 as folding progresses. A model of this extra core interaction, core loop interaction/core loop coalescence which drives folding is proposed.