Table 2.

Data collection and refinement statistics

Complex	H60C_NP1/imidazole	H60C_NP1/histamine
PDB code	1U17	1 U18
Data Collection
Resolution (Å)a	30-1.7 (1.70-1.81)	27-1.96 (2.06-1.96)
Space group	P1 21 1	P1 21 1
Cell a,b,c (Å), β (°)	39.01, 73.99, 65.22; 99.16	38.820, 73.85, 65.38;
Unique reflections	40,082	26,735
Completenessa (%)	99.5 (90.7)	92.5 (70.4)
Multiplicity	3.9 (3.7)	2.1 (1.4)
IΣI	8.1 (1.0)	11.2 (3.4)
Rsymb	0.074 (0.37)	0.038 (0.125)
Refinement
Rcrysc	0.182	0.195
Rfreed (5%)	0.237	0.226
R.m.s.d. bonds (Å)	0.021	0.032
R.m.s.d. angles (Å)	1.96	2.00
ESUe (Å)	0.094	0.130
Atoms: protein (chain A/B)	1447 / 1447	1439 / 1439
Atoms: heme, ligand, (chain	43, 5, 5 / 43, 5, 5	43, 8 / 43, 8
No. waters	310	210
<B> protein (Å2)	23 / 25	35 / 41
<B> heme (Å2)	22 /25	33 / 41
<B> ligand (Å2)	18 /19	32 / 37
<B> water (Å2)	31	38

^aValues in parentheses are for the highest resolution shell

^bR_sym = (Σ_h|I_h-<I>|) / (Σ_h|I_h), where <I> is the mean intensity of all symmetry related reflections I_h.

^cR_crys = (Σ|F_obs-F_calc|) / (ΣF_obs).

^dR_free as for R_crys using a random subset of the data not included in the refinement

^eESU, Estimated overall coordinate error based on maximum likelihood