Instrument Development to Reduce Radiation Damage in Macromolecular Crystallography

开发减少高分子晶体学辐射损伤的仪器

• 批准号: 0650547
• 负责人: Edward Stern
• 金额: $ 53.49万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0650547&HistoricalAwards=false
• 关键词: Instrument; Development; Reduce; Radiation; Damage

This award is for developing instrumentation to reduce the deleterious effects of radiation damage in macromolecular crystallography, which is one of the major limitations in the this field. The instrumentation will be added to synchrotron radiation beamlines. Estimates of potential improvements in crystal survival are 60% for larger crystals and up to a factor of 10 for small platelet-shaped crystals. The basic idea of the strategies is to separate as much as possible the region where diffraction occurs from the region where the damage occurs. This possibility exists, because the primary cause of damage is the energetic photoelectrons (PE's) created by the absorption of x-rays through the photoelectric effect. In bio-crystals that predominantly contain low Z atoms the PE's will have energies about 500 eV less than those of the x-rays, thus typically up to 20 keV. For such energetic PE's the initial stopping power, namely, the energy loss per unit distance, is quite small and increases greatly as they slow down. The distance a 20 keV PE travels is 6 microns. Thus by concentrating the x-rays in small regions separated by slightly more than 6 microns, the goal of separating the diffraction and damaged regions can be accomplished. Any improvement in controlling or reducing primary radiation damage would have major impact on all of macromolecular x-ray crystallography, e.g., opening new crystallography for very large structures, increasing structure resolution of standard sized crystals and obtaining useful structure information from very small platelet-shaped crystals. By reducing damage to crystals during x-ray crystallography, this instrumentation will speed up the accumulation of crystal structures and the understanding of structure-function relationships of biological macromolecules. The project is interdisciplinary, involving physicists and a biologist, and international, involving a physicist from Israel.

该奖项旨在表彰开发仪器以减少大分子晶体学中辐射损伤的有害影响，这是该领域的主要限制之一。该仪器将添加到同步加速器辐射束线中。对于较大的晶体，晶体存活率的潜在改善估计为 60%，而对于小片状晶体则高达 10 倍。该策略的基本思想是尽可能地将发生衍射的区域与发生损坏的区域分开。这种可能性是存在的，因为损坏的主要原因是通过光电效应吸收 X 射线而产生的高能光电子 (PE)。在主要含有低 Z 原子的生物晶体中，PE 的能量比 X 射线的能量低约 500 eV，因此通常高达 20 keV。对于这种充满能量的PE，其初始停止本领（即每单位距离的能量损失）非常小，并且随着它们减速而大大增加。 20 keV PE 的传播距离为 6 微米。因此，通过将X射线集中在间隔略大于6微米的小区域中，可以实现分离衍射区域和受损区域的目的。 控制或减少初级辐射损伤方面的任何改进都会对所有大分子 X 射线晶体学产生重大影响，例如，为非常大的结构开辟新的晶体学，提高标准尺寸晶体的结构分辨率以及从非常小的片状晶体中获得有用的结构信息。通过减少 X 射线晶体学过程中对晶体的损伤，该仪器将加速晶体结构的积累以及对生物大分子结构与功能关系的理解。该项目是跨学科的，涉及物理学家和生物学家，也是国际性的，涉及来自以色列的物理学家。