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Figure 7
Fourier difference density maps of the active site of XI calculated using FFT (Ten Eyck, 1973BB70) through the RIDL pipeline (Bury & Garman, 2018BB14). Here, each Fobs,n − Fobs,1 map has been calculated using the observed structure factor amplitudes |Fobs,n| and |Fobs,1| associated with data sets n and 1, respectively, using the calculated phase set corresponding to the 0.13 MGy low-dose refined coordinate model. The Fobs,n − Fobs,1 maps represent the electron density loss between the lowest-dose data set and each higher-dose data set n > 1. (a, b) Difference density maps for Fobs,2 − Fobs,1 contoured at ±3σ (0.07 e− Å−3), (c, d) for Fobs,7 − Fobs,1 (negative/positive difference densities in red/green, respectively). The increase in damage with increasing dose, especially at the active site and the surroundings of the catalytic metals, is clear. The difference density maps also reflect visually how the electron density around the catalytic metal ion changes. The conformation with the highest occupancy, A, is used by RIDL but, as mentioned in the text, the RIDL analysis is not sensitive enough to detect the radiation damage associated with the small structural changes seen between A and B conformations.

Journal logoJOURNAL OF
SYNCHROTRON
RADIATION
ISSN: 1600-5775
Volume 26| Part 4| July 2019| Pages 931-944
https://doi.org/10.1107/S1600577519005599
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