Table 1.

Crystallographic data

	MAD data			High-resolution data
Space group	P41
Contents of asymmetric unit	2 duplexes of d(CCTAGG) + 2 Ni-TMPy
Unit cell dimensions	a = 32.320 Å c = 62.157 Å			a = 32.210 Å c = 62.259 Å
Maximum resolution, Å	1.59	1.59	1.19	0.86
Wavelength, Å	0.9198	0.9189	0.7747	0.9057
No. of unique reflns*	30,852	8,562	74,396	45,197
|F(hkI)|>4σ
Total no. of reflns	46,441	44,830	120,055	336,951
†Rmerge	1.7%	1.7%	1.4%	2.1%
‡Ranom	7.0%	3.2%	4.2%	4.4%
Phasing statistics	(treated as native)
Phasing power, acentric/centric		4.49/5.45	2.88/2.49
RCullis, acentric/centric		0.29/0.19	0.40/0.36
Mean figure of merit, acentric/centric	0.87/0.85
Refinement statistics
Refinement range, Å				6.0–0.90
R factor all reflns				15.2%
No. of reflns				45,197
R factor for reflns >4σ(F)				14.2%
No. of reflns				37,075
% completeness, R factor for highest-resolution shell				70.3%, 17.4%
Free R factor				16.1%
Total no. of least-squares parameters				3,867
Total no. of atoms				2,360
Number of water molecules				198
Number of magnesium ions				2

 reflns, reflections. 

*Friedel pairs were kept separate for the MAD data and were merged for the high-resolution data used for the refinement. 

^†R_merge is defined as Σ|I − <I>|/ΣI with Bijvoet pairs being treated separately. 

^‡R_anom is defined as R_merge with only Bijvoet pairs now being merged in the calculation.