Table 1.
Refinement statistics
| Crystallographic data | Ternary complex | Binary complex |
|---|---|---|
| Inhibitor bound | Topotecan | — |
| Resolution, Å | 2.1 | 3.2 |
| No. of reflections | 46,866 | 17,874 |
| Rsym | 6.2 | 13.0 |
| Completeness | 81.1 | 85.9 |
| Space group | P21 | P3(2) |
| a | 57.1 Å | 73.2 |
| b | 116.6 Å | 73.2 |
| c | 75.2 Å | 186.6 |
| β | 94.2 | — |
| Reflections used in Rfree | 10% | 10% |
| No. of protein atoms | 4685 | 3498 |
| No. of DNA atoms | 892 | 892 |
| No. of Topotecan atoms | 31 | — |
| No. of solvent atoms | 227 | — |
| No. of PEG atoms | 13 | — |
| Rfactor | 23.2 | 21.7 |
| Rfree | 27.1 | 28.4 |
| rms deviations from ideal stereochemistry | ||
| Bond lengths, Å | 0.0068 | 0.0088 |
| Bond angles, ° | 1.17 | 1.36 |
| Dihedrals, ° | 21.3 | 22.16 |
| Impropers, ° | 3.6 | 3.35 |
| Mean B factor—all atoms, Å3 | 39.3 | 41.8 |
*
Rsym = Σ|li − lm|/Σlm where Ii is the intensity of the measured reflection and Im is the mean intensity of all symmetry-related reflections.
†
Nondrug-bound crystals were merohedrally twinned (twin law h, -h-k, -l; twin fraction = 0.151 estimated using cnx). R factors were calculated using twinned data.