Table 1.

Data Collection, Phasing, and Refinement Statistics

	Se SAD	native
data collection
beamline	SSRL BL9-1	NE-CAT (Sector 8)
wavelength (Å)	0.979	0.979
resolution (Å)	30–2.7	30–2.3
no. of unique observationsa	109776	108695
total no. of observationsa	592029	773692
completeness (%)a	83.0 (49.8)b	100 (100)b
redundancya	5.4 (4.3)b	7.1 (6.9)b
I/σa	17.3 (5.0)b	16.5 (4.9)b
Rsyma,c (%)	5.9 (26.0)b	8.9 (44.8)b
Se sites used for phasing	71 of 77
figure of merit (after density modification)	0.40 (0.75)
refinement
Rwork (%)d	20.2	19.8
Rfree (%)e	25.2	24.2
no. of molecules in ASU	1	1
no. of protein non-hydrogen atoms	16076	15307
no. of non-protein atoms	315	1042
rmsd for bond lengths (Å)	0.033	0.0065
rmsd for bond angles (deg)	2.55	1.28
average B value (Å2)	36.0	37.7

^aValues for the Se SAD data were calculated considering I⁺ and I⁻ as separate reflections.

^bValues in parentheses are for the highestresolution shell.

^c$R_{\mathrm{sym}}={\sum }_i{\sum }_{\mathit{hkl}}\mid I_i\left(\mathit{hkl}\right)-\langle I\left(\mathit{hkl}\right)\rangle \mid ∕{\sum }_{\mathit{hkl}}\langle I\left(\mathit{hkl}\right)\rangle$ , where I_i(hkl) is the ith measured diffraction intensity and 〈I(hkl)〉 is the mean of the intensity for the Miller index (hkl).

^d $R_{\text{work}}={\sum }_{\mathit{hkl}}\mid \mid F_{\mathrm{o}}\left(\mathit{hkl}\right)\mid -\mid F_{\mathrm{c}}\left(\mathit{hkl}\right)\mid \mid ∕{\sum }_{\mathit{hkl}}\mid F_{\mathrm{o}}\left(\mathit{hkl}\right)\mid$

^eR_free = R_work for a test set of reflections (5%).