(c).

Refinement statistics.

Resolution range (Å)	30.0–1.70
Unique reflections	31180
R factor/free R factor‡	0.168/0.205
No. protein atoms	2264
No. water molecules	503
R.m.s. deviations from ideal geometry
Bond lengths (Å)	0.011
Bond angles (°)	1.5
Average isotropic B value (Å2)	16.6

^† R _sym = .

^‡ R factor = − . The free R factor was calculated using 5% of reflections omitted from refinement.