Though our initial analyses of electron beam-induced crystal reorientations were performed on a series of small molecule crystals, we were curious to assess the potential impact of lattice reorientations on more challenging biomolecular targets. To do so, we interrogated microcrystals formed by peptides or proteins: the peptide AVAAGA, the peptidic macrocycle thiostrepton, and the enzyme proteinase K. Biomolecular crystals tend to be substantially more radiation sensitive than most of their small molecule counterparts, often requiring diffraction dose series to be collected from cryogenically preserved stationary crystals. As such, while AVAAGA and thiostrepton crystals could be diffracted dry, proteinase K crystals had to remain hydrated, in a vitrified state. We found stationary AVAAGA peptide crystals to demonstrate evident nonmonotonic intensity fluctuations while illuminated with the electron beam, similar in degree to those seen in biotin at 100K. These crystals displayed the most notable evidence of beaminduced reorientation, followed by thiostrepton, and then proteinase K. Interestingly, crystals of proteinase K appeared to undergo no detectable reorientation during accumulation of 1 e -/Å 2 fluence. Curious to explore if this behavior was a result of the preservation of proteinase K crystals in vitreous ice, we proceeded to collect diffraction series on stationary, vitrified AVAAGA peptide crystals as well. However, these consistently showed a comparable degree of beam-induced reorientation to those diffracted dry, ruling out a role for vitreous ice in fully quenching reorientations (Figure ).