Table 1.

Crystallographic data

Protein	D128A	D128A/biotin
Space group	P21	P21212
Unit cell parameters	a = 48.0, b = 66.3, c = 82.3 Å; β = 97.3°	a = 55.7, b = 84.8, c = 50.0 Å
No. of tetramers per unit cell	2	2
Contents of the asymmetric unit	Tetramer	Dimer
Packing parameter VM, Å3/Da	2.9	2.5
Measured reflections, no.	56,045	39,212
Unique reflections, no.	31,972	14,716
Completeness
Overall, %	85.0	88.0
Outermost shell, %	46.0	43.0
Rmerge overall	0.03	0.05
Refinement
Nonhydrogen atoms, no.	3,416	1,783
Water molecules, no.	178	104
R factor*	0.167	0.156
Free R factor†	0.243	0.243
Average B factor,‡ Å2	32	31
Ramachandran quality§	0.91	0.89

^*For all data with F > 4σ(F), R = Σ_hkl ∥F_o| − |F_c∥/Σ_hkl |F_o|. 

^†For 10% of data with F > 4σ(F). 

^‡For all atoms. 

^§Fraction (except Gly and Pro) in most favored regions (30).