Table 1. Data collection and refinement statistics.
| Data collection and processing statistics | |
| Experiment type | Single-wavelength |
| X-ray source | Diamond light source, beamline I02 |
| Wavelength (Å) | 0.9795 |
| Resolution limits (Å) | 35.00–2.20 (2.32–2.20) |
| Space group | P6 |
| Unit cell parameters (Å,°) | a = b = 241.99 c = 76.59 |
| α = β = 90 γ = 120 | |
| Number of unique reflections | 126842 (18445) |
| Completeness (%) | 98.1 (98.0) |
| I/σ (I) | 10.8 (4.2) |
| Rmerge (%)* | 11.9 (33.8) |
| Refinement statistics | |
| Resolution limits (Å) | 30.00–2.20 (2.26–2.20) |
| R-factor (%) | 17.6 |
| Free R-factor (%) | 21.5 |
| Number of non-H atoms† | 9396 (protein), 1578 (water), 25 (ions) |
| R.m.s.d. bond length (Å) | 0.008 |
| R.m.s.d. bond angles (°) | 1.115 |
| Mean B value (Å2) | 23 |
| Ramachandran plot‡ | |
| Residues in allowed region (%) | 99.7 |
| Residues in disallowed region (%) | 0.3 |
Values in parentheses refer to the highest resolution shell. The crystals of the olokizumab-Fab:IL-6 complex diffracted well, as indicated. However, they proved to be sensitive to X-ray radiation damage – this is not uncommon in crystals of antibody Fab fragments. To take account of the radiation damage, the atoms most affected (mainly sulfur atoms, which form part of cysteine residues) were modeled to reduced occupancy, as suggested in the literature.54 *Rmerge = ∑|Ij – < I > | / Ij, where Ij is the intensity of an individual observation of a reflection and < I > is the average intensity of that reflection. †The crystallographic asymmetric unit contains two copies of the olokizumab-Fab:IL-6 complex. ‡Calculated using the program MolProbity.55 R.m.s.d. = root mean squared deviations.