Howard Hughes Medical Institute, University of California, Los Angeles, Los Angeles CA 90095, USA; Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
Structure. 2018 May 1;26(5):759-766.e4. doi: 10.1016/j.str.2018.03.021. Epub 2018 Apr 26.
Micro-crystal electron diffraction (MicroED) combines the efficiency of electron scattering with diffraction to allow structure determination from nano-sized crystalline samples in cryoelectron microscopy (cryo-EM). It has been used to solve structures of a diverse set of biomolecules and materials, in some cases to sub-atomic resolution. However, little is known about the damaging effects of the electron beam on samples during such measurements. We assess global and site-specific damage from electron radiation on nanocrystals of proteinase K and of a prion hepta-peptide and find that the dynamics of electron-induced damage follow well-established trends observed in X-ray crystallography. Metal ions are perturbed, disulfide bonds are broken, and acidic side chains are decarboxylated while the diffracted intensities decay exponentially with increasing exposure. A better understanding of radiation damage in MicroED improves our assessment and processing of all types of cryo-EM data.
微晶体电子衍射（MicroED）将电子散射的效率与衍射相结合，使结构测定能够从 cryo-EM（冷冻电子显微镜）中的纳米级晶体样品中进行。它已被用于解决各种生物分子和材料的结构问题，在某些情况下达到了亚原子分辨率。然而，对于电子束在这些测量过程中对样品的破坏作用知之甚少。我们评估了蛋白酶 K 和朊病毒七肽纳米晶体的全局和局部损伤，发现电子诱导损伤的动力学遵循在 X 射线晶体学中观察到的成熟趋势。金属离子受到干扰，二硫键断裂，酸性侧链脱羧，而衍射强度随着暴露时间的增加呈指数衰减。更好地了解 MicroED 中的辐射损伤可以提高我们对所有类型 cryo-EM 数据的评估和处理。
