Table II. Refinement statistics.

Resolution range (Å)a	35 to 2.8 (2.9–2.8)
No. of reflections in working set	11 237
No. of reflections in free-R set	991
No. of protein atomsb	1702
No. of solvent molecules	5
No. of metal sites (Ca2+)	2
R-factor (%)c	25.5 (28.7)
Free-R factor (%)d	28.0 (36.4)
R.m.s.d. (bond lengths) (Å)	0.016
R.m.s.d. (bond angles) (°)	1.972
No. of φ, ψ angles (%)e
Most favored	98
Additional allowed	2

^aValues in parentheses refer to data in the highest resolution shell.

^bNon-hydrogen atoms only.

^cR-factor = 100 × Σ(||F_obs| – |F_calc||)/Σ|F_obs|.

^dR_free is the R-factor for a selected subset of reflections (8.1%) that were not included in the refinement calculations.

^eStereochemistry was assessed with PROCHECK (Laskowski et al., 1993).