Figure 6.

Radiation damage for B3C site 1 in proteinase K. The absorbed dose for the crystal is given in MGy (1 Gy = 1 J kg⁻¹). (a) Refined occupancies (SHELXL) for the three Br atoms and the mean value (black) of site 1. The first data point is the occupancy after MAD data collection and a single burn and the subsequent five points show the change in occupancy with increasing dose (see §4.2). A drop in the refined occupancies of about 15% is observed after a dose of 12.9 MGy. (b) Electron density at site 1 contoured at 1σ. The serine residue is used as a reference since its density is not affected by irradiation. The density at the Br atoms clearly decreases with dose, but not all three Br atoms are affected equally.