PT - JOURNAL ARTICLE AU - Hattne, Johan AU - Shi, Dan AU - Glynn, Calina AU - Zee, Chih-Te AU - Gallagher-Jones, Marcus AU - Martynowycz, Michael W. AU - Rodriguez, Jose A. AU - Gonen, Tamir TI - Analysis of global and site-specific radiation damage in cryo-EM AID - 10.1101/258178 DP - 2018 Jan 01 TA - bioRxiv PG - 258178 4099 - http://biorxiv.org/content/early/2018/02/01/258178.short 4100 - http://biorxiv.org/content/early/2018/02/01/258178.full AB - Micro-crystal electron diffraction (MicroED) is an emerging method in cryo-EM for structure determination using nanocrystals. 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.