Table 1. Data-collection and refinement statistics.

Values in parentheses are for the highest resolution shell.

Data set	Apo form	Hg derivative (peak)	Meropenem complex
Data collection
Space group	C2	C2	P212121
Unit-cell parameters
a (Å)	135.6	135.7	68.9
b (Å)	58.6	58.4	73.4
c (Å)	40.9	41.0	104.1
α = γ (°)	90.0	90.0	90.0
β (°)	94.4	94.3	90.0
X-ray wavelength (Å)	1.00000	1.00600	1.00000
Resolution range (Å)	20.0–1.80 (1.83–1.80)	50.0–1.79 (1.82–1.79)	50.0–2.00 (2.03–2.00)
Total No. of reflections	114133 (3344)	218163 (7927)†	254969 (11833)
No. of unique reflections	29426 (1045)	58915 (2557)†	34693 (1621)
Completeness (%)	97.9 (70.4)	99.3 (86.8)†	95.5 (91.2)
〈I/σ(I)〉	46.5 (9.1)	43.0 (7.4)†	31.0 (4.3)
R merge ‡ (%)	4.6 (14.4)	4.6 (14.9)†	12.8 (89.1)
SAD phasing
Figure of merit (before/after density modification)			0.41/0.60
Model refinement
PDB code	4gsq	4gsr	4gsu
Resolution range (Å)	20.0–1.80	20.0–1.79	20.0–2.00
R work/R free § (%)	19.7/23.3	19.6/22.6	18.9/23.2
No. of non-H atoms/average B factor (Å2)
Protein	1889/23.5	2014/23.1	4112/26.4
Water oxygen	206/32.9	230/36.3	228/33.0
Meropenem	—	—	52/65.5
EMTS	—	11/38.0	—
Glycerol	6/53.3	12/44.1	—
Calcium ion	1/65.2	—	—
Wilson B factor (Å2)	21.9	20.4	23.5
R.m.s. deviations from ideal geometry
Bond lengths (Å)	0.009	0.007	0.010
Bond angles (°)	1.29	1.15	1.40
R.m.s. Z-scores¶
Bond lengths	0.450	0.335	0.491
Bond angles	0.590	0.512	0.622
Ramachandran plot†† (%)
Favoured/outliers	98.8/0.0	98.5/0.0	97.9/0.2
Poor rotamers†† (%)	1.00	0.47	0.91

^†Friedel pairs were treated as separate observations.

^‡ R _merge = , where I(hkl) is the intensity of reflection hkl, is the sum over all reflections and is the sum over i measurements of reflection hkl.

^§ R _work = , where R _free is calculated for a randomly chosen 5% of reflections which were not used for structure refinement and R _work is calculated for the remaining reflections.

^¶Values obtained using REFMAC.

^††Values obtained using MolProbity.