Table 2.
Data collection and refinement statistics
| HPRT | HPRT-IMP | HPRT-GMP | |
| Data collection | |||
| Temperature (K) | 100 | 100 | 100 |
| Unit cell length (Å) | a = b = 83.9, c = 169.4 | a = b = 84.1, c = 167.3 | a = b = 84.1, c = 167.3 |
| Unit cell angle (°) | α = β = 90 γ = 120 | α = β = 90 γ = 120 | α = β = 90 γ = 120 |
| Space group | P3121 | P3121 | P3121 |
| Resolution range (Å) | 50.0–2.9 | 50.0–2.8 | 50.0–2.8 |
| Unique reflections [I > 0σ(I)] | 14,653 | 17,473 | 15,697 |
| Total observations [I > 0σ(I)] | 60.922 | 58,776 | 45,289 |
| Completeness (%) | 92.0 (56.0) | 99.7 (99.8) | 88.9 (89.8) |
| Rsym (%)a | 0.103 (0.293) | 0.071 (0.276) | 0.072 (0.294) |
| ≤I>/≤σ(I)> | 7.2 (2.8) | 8.7 (4.5) | 9.1 (4.1) |
| Tetramers per asymmetric unit | 1/2 | 1/2 | 1/2 |
| Solvent content (%) | 70.6 | 70.3 | 70.3 |
| Refinement | |||
| Resolution range (Å) | 50.0–2.9 | 50.0–2.8 | 50.0–2.8 |
| Rfactor [F > 0σ(F)]b | 0.214 | 0.201 | 0.199 |
| Rfree [F > 0σ(F)]b | 0.238 | 0.243 | 0.244 |
| Average B-factor (Å2) | 30.8 | 41.7 | 37.5 |
| RMS deviations from ideal | |||
| Bond length (Å) | 0.007 | 0.006 | 0.007 |
| Bond angle (°) | 1.37 | 1.37 | 1.38 |
| Ramachandran plot statistics | |||
| Residues in most favored regions (%) | 88.9 | 87.2 | 86.5 |
| Total number | 264 | 262 | 258 |
| Residues in disallowed regions (%) | 0.0 | 0.3 | 0.3 |
| Total number | 0 | 1 | 1 |
Values in parentheses are for the outer shell of data; 3.0–2.9 Å for the free enzyme and 2.90–2.80 Å for the HPRT-IMP and HPRT-GMP complexes.
a Rsym = ∑|I = ≤I>|/∑≤I>.
b Rfactor = ∑∥Fobs| − |Fcalc∥/∑|Fobs|, where the Rfactor is calculated based on the reflections used in the refinement (90% of the total data) and Rfree (Brünger 1992a) is calculated using the remaining 10% of the data.