IMPROVING BROMIDE SOAKS FOR SOLVING THE PHASE PROBLEM IN CRYSTALLOGRAPHY

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目及 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可以在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 有许多哺乳动物蛋白不能用硒-蛋氨酸细菌表达系统产生。对于这些蛋白质，相位问题可以通过添加重原子并利用它们的微分散射来获得相位信息并产生电子密度来解决。本文介绍了Z. Dauter（NSLS）是Se-Met定相的一种替代方法。用高浓度溴化物或碘化物溶液短时间浸泡蛋白质晶体会产生表面结合离子。 不幸的是，这种修改方法效率低。由于渗透压的差异，卤化物浸泡通常会对蛋白质晶格产生应力。 正在开发将RbBr引入覆盖在油中的样品的方法。 有迹象表明，这种方法提供了精确的控制和精确的输送，最大限度地减少了对晶体的物理和化学冲击。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. There are number of mammalian proteins that cannot be produced with Se-Methionine bacterial expression systems. For those proteins the phase problem could be solved by adding heavy atoms and use their differential scattering to obtain phase information and generate electron density. The method of halide soaking pioneered by Z. Dauter (NSLS) is one alternative to the Se-Met phasing. Short soaking of the protein crystals with high concentration bromide or iodide solutions results in a surface bound ions. Unfortunately, this modification method suffers from low efficiency. Halide soaking often stresses the protein crystal lattice due to differences in osmotic pressure. Methods for introducing RbBr to the sample covered in oil are being developed. Indications are that this approach offers precise control and pinpoint delivery, minimizing physical and chemical shock to the crystal.