Table 1.
Summary of crystallographic analysis
| Diffraction data and phasing statistics | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Data Set | Crystals | Resolution, Å | Unique reflections | Completeness, % | Redundancy | 〈I/σI〉 | Rmerge, % | Sites | Rderiv, % | Rc, % | Phasing power |
| Native | 2 | 30-4.0 | 16,089 | 85 (50) | 3.6 (1.3) | 3.7 (0.9) | 16.6 (73.2) | – | – | – | – |
| PIP39 | 2 | 24-4.2 | 13,760 | 84 (31) | 5.9 (2.2) | 3.8 (1.5) | 17.0 (46.0) | 7 | 37 | 62 | 1.32/0.96 |
| PIP4 | 1 | 75-4.5 | 11,678 | 89 (61) | 4.1 (1.8) | 2.9 (1.9) | 17.0 (34.7) | 6 | 24 | 64 | 1.23/0.88 |
| Averaging statistics | |||||
|---|---|---|---|---|---|
|
|
〈FOM〉 | 〈Δϕ〉 | FO/FCR, % | FO/FC CC, % | Map CC, % |
| Before averaging | 0.45 | – | 36.7 | 77.0 | 51.2 |
| After averaging | 0.75 | 58° | 10.6 | 98.6 | 90.7 |
| Refinement statistics | ||||||||
|---|---|---|---|---|---|---|---|---|
| Resolution, Å | Reflections | Rcryst, % | Rfree, % | Atoms | Bond length dev., rms | Bond angle dev., rms | Ramachandran outliers, residues | |
| F > 2σF | 27-4.0 | 15,543 | 38.2 (43.0) | 42.8 (46.2) | 3,294 | 0.010 Å | 1.66° | 31 of 402 |
Rmerge = Σ|I − 〈I〉|/ΣI, where I is the observed intensity and 〈I〉 is the average intensity of multiple observations of symmetry-related reflections. Numbers in parentheses refer to those data in the highest resolution shell (4.22–4.00 Å for the native data set).
Rderiv = Σ||FPH| − |FP||/Σ|FP|, where |FP| and |FPH| are the observed native and heavy-atom derivative structure factor amplitudes.
RC = Σ||FPH ± FP| − FH|/Σ|FPH ± FP|, where FH is the calculated heavy-atom structure factor amplitude; calculated for centric reflections only.
Phasing power = rms (|FH|/E), where E is the residual lack of closure error; listed for acentric/centric reflections.
FOM (mean figure of merit) = 〈ΣP(α)eiα/ΣP(α)〉, where α is the phase and P(α) is the phase probability distribution.
〈Δϕ〉 = rms phase change.
CC = [ΣFOFC − (ΣFOΣFC)/N]/{[ΣFO2 − (ΣFO)2/N][ΣFC2 − (ΣFC)2/N]}½, where |FO| and |FC| are the observed and calculated structure factor amplitudes, and N is the number of reflections.
R = Σ||FO| − |FC||/Σ|FO|; Rfree is calculated for a randomly-selected 5% of the reflections; Rcryst is calculated for the remaining 95% of the reflections used in refinement.