PERFORMING TWO WAVELENGTH MAD EXPERIMENT WITHOUT CHANGING ENERGY

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 提出了一种在不改变能量的情况下进行双波长MAD实验的新方法。这种新的方法利用了同步加速器存储环的固有特性，其中多个谐波能量从单色器入射。在典型的结晶学实验中，高次谐波被认为是“不需要的”，并使用镀金属或未镀膜的反射镜来排除。通过适当选择入射能量和镜面，我们能够将两个能量(边缘能量和远距离能量)入射到Gd浸渍的蛋白酶K晶体上，并收集了两个波长的MAD数据集。我们还能够证明，与SAD实验相比，这些MAD实验可以获得更高质量的电子密度图。描述这项实验的手稿正在准备中。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. A novel method of performing two wavelength MAD experiment without changing energy was developed. This novel method utilizes the inherent property of a synchrotron storage ring, where multiple harmonic energies are incident from the monochromator. During a typical crystallography experiment, the higher harmonics are considered "undesired" and rejected using a metal coated or un-coated mirror. By appropriate choice of incident energy and mirror surface, we were able to incident two energies (edge and far remote) on a gadolinium soaked Proteinase K crystal and collect a two wavelength MAD dataset. We were also able to show that superior quality electron density maps could be obtained from these MAD experiments as compared to those from a SAD experiment. A manuscript describing this experiment is in preparation.