Chen Z, Chapman M S
Department of Physics, Florida State University, Tallahassee, Florida 32306, USA.
Biophys J. 2001 Mar;80(3):1466-72. doi: 10.1016/S0006-3495(01)76118-8.
Motion is critical to the function of many proteins, but much more difficult to study than structure. Due to lack of easy alternatives, although there are inherent limitations, there have been several prior attempts to extract some information from the Bragg scattering in conventional diffraction patterns. Bragg diffraction reflects only a small proportion of a protein's motion and disorder, so fitted values likely underestimate reality. However, this work shows that the fitted estimates should be even smaller, because current methods of refinement over-fit the Bragg diffraction, leading to a component of the disorder that is not based on any experimental data, and could be characterized as a guess. Real-space refinement is less susceptible than other methods, but its application depends on the availability of very accurate experimental phases. A future challenge will be the collection of such data without resort to cryo-techniques, so that a physiologically relevant understanding can be achieved.
运动对许多蛋白质的功能至关重要，但比结构研究困难得多。由于缺乏简便的替代方法，尽管存在固有局限性，但此前已有多次尝试从传统衍射图案中的布拉格散射提取一些信息。布拉格衍射仅反映了蛋白质运动和无序的一小部分，因此拟合值可能低估了实际情况。然而，这项工作表明，拟合估计值应该更小，因为当前的精修方法对布拉格衍射过度拟合，导致无序的一个组成部分并非基于任何实验数据，可被视为一种猜测。实空间精修比其他方法更不易受影响，但其应用取决于非常精确的实验相位的可用性。未来的一个挑战将是在不借助冷冻技术的情况下收集此类数据，以便能够实现对生理相关情况的理解。
