Fig. 5
Difference electron density maps of different phycocyanin datasets. To assess the influence of phase bias introduced by the search model, we mutated residues 152 and 153 of chain A of Phyco A1 (single chip/single pulse, a, pink), Phyco B (five chips merged, single pulse, e, cyan), and Phyco C (single chip, multi-bunch exposure, i, green) and calculated simulated annealing maps (all blue maps are 2mFo − DFc maps at 1.5 sigma, all green and red maps are mFo − DFc maps at 2.5 sigma). We furthermore deleted residues 147–157 of chain B for all three cases and calculated a simulated annealing omit map (b, f, j). Here we also show the omitted residues for clarity. In all three cases strong positive difference electron density is visible in the map in place of the omitted residues. To show that the mode of data collection does not lead to local radiation damage, we show the 2mFo − DFc map (c, g, k) and the mFo − DFc map (c, g, k) and (d, h, l) for the bond between Cys84 of chain A and the phycocyanobilin-ligand for all three cases. No difference electron density is visible around the S–C-bond in any of the cases
