CRYSTALLOGRAPHIC DESCRIPTION OF THE PHOTOINTERMEDIATES OF BACTERIORHODOPSIN

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。我们在立方脂相中生长的细菌视紫红质晶体的衍射率接近1.4°，并有望提供关于这种光驱动质子泵的反应周期中间体K、L、M、N和O的结构信息。在不同条件下照射野生型和突变型晶体，可以产生少数M亚态，占有率为100%，但大多数中间态仅积累到40%-60%。改进模型中的第二种构象是困难的，对结论的信心取决于来自大量重复实验的高分辨率数据。我们收集的1.43°分辨率的数据集一直令人鼓舞，并提供了关于K状态下视网膜发色团扭曲及其在早期M状态下的变化的初步信息。我们建议用现有的最好的同步加速器束继续这些实验，并首次对任何离子泵的传输机制进行详细的分子描述。

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. Bacteriorhodopsin crystals we have grown in cubic lipid phase diffract to nearly 1.4 ¿¿ and promise to yield structural information on the reaction cycle intermediates, K, L, M, N and O, of this light-driven proton pump. By illumination of wild-type and mutant crystals under various conditions, a few M sub-states could be produced with 100% occupancy, but most intermediates accumulate to 40-60% only. Refinement of the second conformation in the models is difficult, and confidence in the conclusions depends on high-resolution data from numerous duplicate experiments. Data sets we collected to 1.43 ¿¿resolution have been encouraging, and produced preliminary information about the twisted retinal chromophore in the K state and its changes in an early M state. We propose to continue these experiments with the best synchrotron beam available, and to describe, for the first time for any ion pump, the transport mechanism in detailed molecular terms.