RT Journal Article SR Electronic T1 MicroED Structures from Micrometer Thick Protein Crystals JF bioRxiv FD Cold Spring Harbor Laboratory SP 152504 DO 10.1101/152504 A1 Martynowycz, Michael W. A1 Glynn, Calina A1 Miao, Jennifer A1 Jason de la Cruz, M. A1 Hattne, Johan A1 Shi, Dan A1 Cascio, Duilio A1 Rodriguez, Jose A1 Gonen, Tamir YR 2017 UL http://biorxiv.org/content/early/2017/06/20/152504.abstract AB Theoretical calculations suggest that crystals exceeding 100 nm thickness are excluded by dynamical scattering from successful structure determination using microcrystal electron diffraction (MicroED). These calculations are at odds with experimental results where MicroED structures have been determined from significantly thicker crystals. Here we systematically evaluate the influence of thickness on the accuracy of MicroED intensities and the ability to determine structures from protein crystals one micrometer thick. To do so, we compare ab initio structures of a human prion protein segment determined from thin crystals to those determined from crystals up to one micrometer thick. We also compare molecular replacement solutions from crystals of varying thickness for a larger globular protein, proteinase K. Our results indicate that structures can be reliably determined from crystals at least an order of magnitude thicker than previously suggested by simulation, opening the possibility for an even broader range of MicroED experiments.Summary Atomic resolution protein structures can be determined by MicroED from crystals that surpass the theoretical maximum thickness limit by an order of magnitude.