MAD USING MEDIUM ANGLE X-RAY SOLUTION SCATTERING (MADMAX)

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 该项目使用了一种新的方法，即使用中角X射线溶液散射的多波长异常衍射(MADMAX)，用于精确测量蛋白质和其他水溶液中的大分子的原子间距离。我们的初步实验表明，可以从溶液中的蛋白质中测量到异常差异。在钾通道KCSA的溶液散射中观察到与硒的散射不同；在从血红蛋白的散射中观察到与铁的不同。这项工作得到了NIH Eureka奖(高度创新的研究)的支持，以支持这项技术的发展。最近，我们开发了一种计算广角X射线溶液散射(WAXS)的方法，该方法使用水的显式原子表示(Park等人，2009)。这不需要参数的拟合)允许我们计算WAXS模式以在实验误差范围内来测试蛋白质结构的模型。我们现在已经将这一能力扩展到包括计算蛋白质的反常散射成分(Bardhan和Makowski，未发表)。这大大增加了MadMax的能力，使我们能够预测当蛋白质中存在多个异常散射原子时的异常差异。目前，我们正在收集已知结构的硒蛋氨酸标记蛋白质的反常散射，以确定该方法对具有1个或2个或6-10个硒标记的蛋白质的能力。

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. This project involves use of a new method, Multi-wavelength Anomalous Diffraction (MADMAX) using Medium Angle X-ray solution scattering (MADMAX), for the precise measurement of interatomic distances within proteins and other macromolecules in aqueous solution. Our preliminary experiments have shown that anomalous differences can be measured from proteins in solution. Differences from selenium scatter have been observed in solution scattering from the potassium channel, kcsa; differences from iron have been observed in scattering from hemoglobin. The work is supported by an NIH Eureka award (for highly innovative research) to support the development of this technique. Recently, we developed a method for computing wide-angle x-ray solution scattering (WAXS) from atomic coordinate sets using an explicit atom representation of water (Park et al.,2009). This, which requires no fitting of parameters) allows us to calculate WAXS patterns to within experimental error to test models for protein structure. We have now extended that capability to include calculation of the anomalous scattering components of proteins (Bardhan and Makowski, unpublished). This greatly increases the power of MADMAX, allowing us to predict the anomalous differences when there are multiple anomalous scattering atoms in the protein. Currently we are collecting anomalous scattering from selenomethionine-labelled proteins of known structure to determine the power of the method for proteins with 1 or 2 or 6-10 selenium labels.