Table 3. Refinement statistics.

Refinement
Resolution range (Å)	25.0–2.7
No. of reflections used for refinement	19520
No. of reflections used for Rfree	894
R factor†	0.234 (0.358)
Rfree‡	0.273 (0.363)
R.m.s. bonds (Å)	0.007
R.m.s. angles (°)	1.2
No. of non-H atoms	4777 plus 4 Ni2+ ions
Average B factor (Å2)	73.2
R.m.s.d. B factor for bonded main-chain atoms (Å2)	6.3
R.m.s.d. B factor for bonded side-chain atoms (Å2)	9.3
R.m.s.d. B factor for angle main-chain atoms (Å2)	10.2
R.m.s.d. B factor for angle side-chain atoms (Å2)	13.9
Cruickshank DPI (Å)	0.40
Ramachandran plot (PROCHECK)
Residues in most favored region	467 (87.8%)
Residues in additional allowed regions	59 (11.1%)
Disallowed regions	3 (0.6%)

^† R = .

^‡ R _free was calculated using a 5% randomly selected subset of the total number of reflections.