Table 1. X-ray Data Collection and Refinement Statistics.
| D394A mutein with α-maltose 1-phosphate | E423A mutein with maltose (control) | E423A mutein with a 2-deoxy-2-fluoro-β-maltosyl modification | |
|---|---|---|---|
| Data Collection | |||
| beamline | I24 | I04-1 | I04-1 |
| wavelength (Å) | 0.978 | 0.917 | 0.917 |
| detector | Pilatus 6M | Pilatus 2M | Pilatus 2M |
| resolution rangea (Å) | 104.53–2.55 (2.62–2.55) | 37.78–2.29 (2.35–2.29) | 50.54–2.40 (2.47–2.40) |
| space group | P41212 | P41212 | P41212 |
| cell parameters (Å) | a = b = 113.52, c = 313.60 | a = b = 114.18, c = 313.64 | a = b = 113.00, c = 313.86 |
| total no. of measured intensitiesa | 949841 (65056) | 1007908 (73110) | 582247 (40239) |
| no. of unique reflectionsa | 67726 (4748) | 93835 (6826) | 79517 (5527) |
| multiplicitya | 14.0 (13.7) | 10.7 (10.7) | 7.3 (7.3) |
| mean I/σ(I)a | 11.4 (3.0) | 15.4 (3.0) | 14.7 (2.0) |
| completenessa (%) | 99.7 (96.6) | 99.9 (99.9) | 99.5 (95.3) |
| Rmergea,b | 0.169 (0.659) | 0.088 (0.576) | 0.094 (0.991) |
| Rmeasa,c | 0.192 (0.564) | 0.097 (0.634) | 0.109 (1.150) |
| CC1/2a,d | 0.998 (0.804) | 0.999 (0.882) | 0.998 (0.657) |
| Wilson B value (Å2) | 54.1 | 51.1 | 43.7 |
| Refinement | |||
| resolution rangea (Å) | 91.95–2.55 (2.62–2.55) | 37.78–2.29 (2.35–2.29) | 50.54–2.40 (2.47–2.40) |
| no. of reflectionse | |||
| working | 64195 | 89028 | 75425 |
| free | 3423 | 4697 | 3985 |
| Rwork/Rfreea,f | 0.185/0.215 (0.275/0.328) | 0.195/0.220 (0.331/0.335) | 0.184/0.208 (0.335/0.355) |
| Ramachandrang (%) | |||
| favored | 97.9 | 97.9 | 98.0 |
| allowed | 1.8 | 2.1 | 1.8 |
| disallowed | 0.3 | 0.0 | 0.2 |
| root-mean-square deviation for bond distances (Å) | 0.011 | 0.011 | 0.011 |
| root-mean-square deviation for bond angles (deg) | 1.41 | 1.36 | 1.36 |
| no. of protein residues (ranges) (chain A, chain B) | 649 (15–663), 649 (15–663) | 649 (15–663), 649 (15–663) | 649 (15–663), 649 (15–663) |
| no. of water molecules | 437 | 480 | 418 |
| no. of ligand molecules | 2 | 2 | 2 |
| mean B factor (Å2) | |||
| protein | 45.3 | 52.4 | 53.4 |
| water | 37.5 | 43.9 | 43.2 |
| ligand | 54.1 | 45.6 | 47.2 |
| overall | 45.0 | 52.0 | 53.0 |
| Protein Data Bank entry | 4CN1 | 4CN6 | 4CN4 |
Figures in parentheses indicate values for the outer resolution shell.
Rmerge = ∑hkl∑i|Ii(hkl) – ⟨I(hkl)⟩|/∑hkl∑iIi(hkl).
Rmeas = ∑hkl[N/(N – 1)]1/2 × ∑i|Ii(hkl) – ⟨I(hkl)⟩|/∑hkl∑iIi(hkl), where Ii(hkl) is the ith observation of reflection hkl, ⟨I(hkl)⟩ is the weighted average intensity for all observations i of reflection hkl, and N is the number of observations of reflection hkl.
CC1/2 is the correlation coefficient between intensities taken from random halves of the data set.
The data set was split into “working” and “free” sets consisting of 95 and 5% of the data, respectively. The free set was not used for refinement.
Rwork and Rfree were calculated as follows: R = ∑(|Fobs – Fcalc|)/∑|Fobs| × 100, where Fobs and Fcalc are the observed and calculated structure factor amplitudes, respectively.
As calculated using MolProbity.51