Table 1.

Data collection and refinement statistics

Data collection
X-ray source	APS GM/CA 23ID-D
X-ray wavelength (Å)	0.98
Space group	P3221
Cell dimensions
a=b, c (Å)	52.52; 227.17
Molecules in asymmetric unit	2
Wilson B-factor (Å2)	26.9
Resolution (Å)	75.7–2.0
Rmergea,b	0.098 (0.587)
〈I〉/〈σ(I)〉	21.1 (1.8)
Completeness (%)	97.3 (83.9)
Redundancy	8.5 (5.1)
Refinement
PDB code	4E08
Program	Refmac5.6.0116
No. unique reflections	23814
Rwork; Rfree(%)c,d	19.3; 24.6
Average B-factor (Å2)
Chain A; B	30.8; 31.4
Solvent	37.3
r.m.s.d
Bond length (Å)	0.016
Bond angles (deg.)	1.503
Ramachandran plot: favored; allowed; forbidden (%)	99.2; 99.7; 0.27

^aValues in parentheses are for highest-resolution shell (2.07–2.00 Å).

^b $R_{\mathit{merge}}={\displaystyle \sum _{\mathit{hkl}}}{\displaystyle \sum _i}\mid I_{\mathit{hkl}}^i-\langle I_{\mathit{hkl}}\rangle \mid /{\displaystyle \sum _{\mathit{hkl}}}{\displaystyle \sum _i}{I}_{\mathit{hkl}}^i$, where i is the i^th observation of a reflection with indices h,k,l and angle brackets indicate the average over all i observations.

^c $R_{\mathit{work}}={\displaystyle \sum _{\mathit{hkl}}}\mid F_{\mathit{hkl}}^o-F_{\mathit{hkl}}^c\mid /{\displaystyle \sum _{\mathit{hkl}}}{F}_{\mathit{hkl}}^o$, where F^c_hkl is the calculated structure factor amplitude with index h,k,l and F^o_hkl is the observed structure factor amplitude with index h,k,l.

^dR_free is calculated as R_work, where the F^o_hkl are taken from a test set comprising 5% of the data that were excluded from the refinement.