Table 3. Refinement statistics.

Data set	pH 4.5	pH 5.5	pH 7.0	0.98 Å	1.38 Å
Rwork/Rfree (%)	19.72/22.67	15.36/18.72	18.86/22.46	18.56/22.38	15.76/19.48
Contents of asymmetric unit
Protein atoms	496	496	496	496	496
Copper ions	3	4	4	3	2
Water molecules	312	606	312	415	652
R.m.s.d. from ideal
Bond lengths (Å)	0.010	0.012	0.010	0.025	0.007
Bond angles (°)	1.34	1.50	1.279	2.12	1.367
Mean overall B value (Å2)
Protein	25.80	13.98	24.82	23.22	16.56
Solvent	30.18	26.72	29.59	31.06	28.82
Ramachandran plot, residues in
Most favoured regions	463 (93.91%)	467 (94.72%)	464 (94.12%)	464 (94.12%)	465 (94.32%)
Additionally allowed regions	28 (5.68%)	24 (4.86%)	27 (5.48%)	27 (5.48%)	26 (5.07%)
Outliers	2 (0.41%)	2 (0.41%)	2 (0.41%)	2 (0.41%)	2 (0.41%)
Estimated absorbed dose (MGy)	0.2	0.6	0.3	16	5.9
PDB code	4a2d	4a2e	4a2h	4a2f	4a2g
No. of images collected (Δϕ = 0.5°)	180	198	200	250	200