Table 1.

Statistics on diffraction data and structure refinement

Data collection	PDE9-1r	PDE9-1s
Space group	P41212	P41212
Unit cell (a, c, Å)	103.2, 270.8	103.3, 271.1
Resolution (Å)	2.7	2.5
Total measurements	453,044	578,551
Unique reflections	41,185	51,787
Completeness (%)	100.0 (100.0)*	99.9(100.0)*
Average I/σ	12.2 (4.8)*	12.6 (4.8)*
Rmerge	0.084 (0.59)*	0.081 (0.57)*
Structure Refinement
R-factor	0.230	0.223
R-free	0.258 (10.0%)‡	0.245
Resolution (Å)	15–2.7	15–2.5
Reflections	39,257	49,441
RMS deviation for
Bond	0.007 Å	0.007
Angle	1.3°	1.2°
Average B-factor (Å2)
Protein	57.4 (5264)§	51.5 (5288)
Inhibitor	45.7 (48)	44.9 (48)
Zn	46.0 (2)	53.5 (2)
Mg	43.5 (2)	37.6 (2)
Water	39.7 (16)	36.2 (16)

^*The numbers in parentheses are for the highest resolution shell.

^‡The percentage of reflections omitted for calculation of R-free.

^§The number of atoms in the crystallographic asymmetric unit.