Table 2.

Crystallographic data collection and refinement statistics

Form	Temperature of data collection	Resolution, Å	Total reflections	Unique reflections	Completeness*	Rmerge†, %	Form	Asymmetric unit	Rcryst‡, %	Rfree§, %	No. solvent	rms bond lengths, Å	rms bond angles
II	−160°	2.16	50,635	21,638	82% (41%)	4.8	II	One dimer	23.1	31.6	248	0.012	2.1°
IV	Room temperature	2.61	96,208	18,023	78% (50%)	10.3		One DNA duplex
							IV	One dimer	18.1	30.2	71	0.011	1.8°
								One DNA duplex

*Completeness in the highest resolution shell is given in parentheses. 

^†R_merge = (Σ_hΣ_i|〈F_h〉 − F_hi|)/(Σ_hF_h), where 〈F_h〉 is the mean structure factor magnitude of i observations of symmetry-related reflections with Bragg index h. 

^‡R_cryst = (Σ_hΣ_i||F_obs| − |F_calc||)/(Σ|F_obs|), where F_obs and F_calc are the observed and calculated structure factor magnitudes. 

^§R_free is calculated with removal of 5% of the data as the test set, followed by simulated-annealing refinement of the final model.