PHASING MACROMOLECULAR STRUCTURES

总的目标是扩大我们对大分子的认识， 通过减少所需的时间和精力， 来确定生物分子的三维结构。 的 研究重点是蛋白质晶体学，旨在开发两种 新的分阶段技术，使其潜力可以充分发挥 被剥削 其中一种技术，直接方法与异常 散射，看起来很有前途，最近被用于结构 镉、锌金属硫蛋白的测定。 另一种技术，直接 方法与单一的同构替换，看起来像是甚至 更强大 在这两种技术中，一般理论（由诺贝尔 获奖者赫伯特豪普特曼）已得到确认，并在一个 基本的方式，但在程序可以 常规使用。 这项建议的具体目的是 克服这些障碍，如下：（1）建立限制 新程序的适用性;（2）完善直接法 通过实施和评估确定 新理论预测值的各个阶段;（3）到 分析和评估结果，从唯一的实际应用， 直接法--迄今为止的反常散射法;（4）评价 提出了一种新的直接方法--单同构加细理论， 应用真实的（实验）数据;（5）检查 将新程序与现有的分期方法结合起来;（6） 开发一个有效的，可导出的计算机程序系统， 以自动化的方式执行程序，并提供有关 实际执行问题。 新技术比现有方法有几个优点。 他们 应该为确定三维结构提供了强有力的工具 生物或健康相关的化合物。 由于目前的程序 一般需要多年的努力，任何技术，可以加快 过程将受到欢迎。

The overall objective is to extend our knowledge of macromolecular structure-function relationships by reducing the time and effort required to determine three-dimensional structures of biological molecules. The research focuses on protein crystallography and is aimed at developing two new phasing techniques to the point where their potentials can be fully exploited. One of the techniques, direct methods with anomalous scattering, looks promising and was recently used in the structure determination of Cd,Zn metallothionein. The other technique, direct methods with single isomorphous replacement, looks like it will be even more powerful. In both techniques, the general theory (developed by Nobel Laureate Herbert Hauptman) has been confirmed and implemented in a rudimentary fashion, but several hurdles remain before the procedures can be used routinely. The specific aims of this proposal are designed to overcome those hurdles and are as follows: (1) to establish the limits of applicability of the new procedures; (2) to complete the direct methods phasing process by implementing and evaluating procedures for determining individual phases from the values predicted by the new theories; (3) to analyze and evaluate results from the only practical application of the direct methods-anomalous scattering procedure to date; (4) to evaluate the new direct methods-single isomorphous refinement theory and make the first application with real (experimental) data; (5) to examine ways of integrating the new procedures with existing phasing methods; (6) to develop an efficient, exportable computer program system for carrying out the procedures in an automated fashion, and to provide feedback regarding practical implementation problems. The new techniques have several advantages over existing methods. They should provide powerful tools for determining three-dimensional structures of biological or health-related compounds. Since the current procedures generally require years of effort, any technique which can expedite the process would be welcomed.