CRYSTALLOGRAPHIC DESCRIPTION OF THE PHOTOINTERMEDIATES OF BACTERIORHODOPSIN

该子项目是利用 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得主要资金， 因此可以在其他CRISP条目中表示。列出的机构是 中心，不一定是研究者的机构。 我们在立方脂质相中生长的细菌视紫红质晶体的电导率接近1.4 Ω，并有望产生这种光驱动质子泵的反应循环中间体K，L，M，N和O的结构信息。通过在各种条件下照射野生型和突变体晶体，可以产生具有100%占有率的少数M亚态，但大多数中间体仅积累到40-60%。模型中第二构象的精确化是困难的，结论的可信度取决于来自大量重复实验的高分辨率数据。我们收集到的分辨率为1.43 <$的数据集令人鼓舞，并产生了关于K状态下扭曲的视网膜发色团及其在早期M状态下变化的初步信息。我们建议继续这些实验与最好的同步加速器光束，并描述，第一次为任何离子泵，详细的分子方面的传输机制。

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.