Experimental phasing of MicroED data using radiation damage

We present an example of an experimentally phased structure using only MicroED. The structure of a seven-residue peptide is determined starting from differences to the diffraction intensities induced by structural changes due to radiation damage. The same wedge of reciprocal space was recorded twice by continuous rotation MicroED from a set of 11 individual crystals. The data from the first pass were merged to make a “low-dose dataset”. The data from the second pass were similarly merged to form a “damaged dataset.” Differences between these two datasets were used to calculate a Patterson difference map and to identify a single heavy atom site, from which initial phases were generated. The structure was then completed by iterative cycles of modeling and refinement.