PHASING MACROMOLECULAR STRUCTURES

总体目标是扩展我们对大分子的认识。 通过减少所需的时间和精力来实现结构与功能的关系 来确定生物分子的三维结构。这个 研究重点是蛋白质结晶学，目的是开发两种 新的相移技术，使其潜力得以充分发挥 被剥削。其中一种技术是使用异常的直接方法 散射，看起来很有希望，最近在结构中使用 镉、锌金属硫蛋白的测定。另一种技术是直接 具有单一同构替换的方法，看起来将是均匀的 更强大。在这两种技术中，一般理论(由诺贝尔开发 诺贝尔奖获得者赫伯特·豪普特曼)已被确认并在 初步的方式，但仍有几个障碍，程序可以 被常规使用。这项提案的具体目标旨在 克服这些障碍并如下所述：(1)确定 新程序的适用性；(2)完善直接法 通过实施和评估确定程序的分阶段进程 从新理论预测的值中分离出单独的阶段； 分析和评估唯一实际应用的结果 直接法-迄今的异常散射程序；(4)评估 新的直接方法--单同构精化理论并使之成为第一 实际(实验)数据的应用；(5)检验方法 将新程序与现有分期方法相结合；(6) 开发一种高效、可导出的计算机程序系统，用于执行 以自动化的方式提供程序，并就以下方面提供反馈 实际执行中的问题。 与现有方法相比，新技术有几个优点。他们 应该为确定三维结构提供强大的工具 生物或与健康相关的化合物。由于目前的程序 通常需要多年的努力，任何可以加快 这一进程将是受欢迎的。

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.