Table I.
Crystallographic Data Collection and Refinement Statistics for His-418 Substituted β-Galactosidases
| Variant | Resolution (Å) | <I>/<σ> | Completeness (%) | Redundancy | Rsym (%) | Rmeas (%) |
|---|---|---|---|---|---|---|
| H418N | 28.7–1.75 | 10.8 (4.2) | 96.8 (84.5) | 2.7 | 4.4 (17.3) | 5.4 (21.3) |
| H418N/IPTG | 30.0–1.80 | 6.9 (2.0) | 98.0 (94.6) | 3.2 | 8.9 (42.2) | 7.6 (36.2) |
| H418E | 34.5–2.05 | 7.9 (2.4) | 99.4 (98.2) | 2.6 | 8.0 (31.6) | 10.0 (40.1) |
| H418E/Gal | 500–3.0 | 5.1 (1.6) | 91.7 (94.2) | 1.8 | 12.3 (47.8) | 74 (67) |
| Deviations from ideal values |
||||||
| Cell parameters (Å) | Wilson B-factor (Å2) | R-Factor (%) | Bond lengths (Å) | Bond angles (degrees) | Avg B (MC protein, Å2) | |
| H418N | 149.4 168.0 200.3 | 15.4 | 15.9 | 0.017 | 2.85 | 19.3 |
| H418N/IPTG | 152.0 162.5 204.0 | 18.9 | 17.3 | 0.016 | 2.83 | 21.6 |
| H418E | 149.3 167.2 200.4 | 20.1 | 15.8 | 0.015 | 2.88 | 23.8 |
| H418E/Gala | 128.4 152.9 132.1 | 60.0 | 21.8 | 0.007 | 1.37 | 42.3 |
| Nativeb | 16.8 | |||||
| Native/IPTG | 22.4 | |||||
Data for (H418N, H418N/IPTG and H418E) were collected at the Stanford Synchrotron Radiation Laboratory Beamline 7-1. Data for H418E/Gal were collected at the Advanced Light Source in Berkeley (California) at beamline 8.3.1 under agreement with the Alberta Synchrotron Institute* and processed using Mosflm and Scala. <I>/<σ> gives the average intensity relative to the average uncertainty, with the high resolution bin in parentheses. Rsym gives the agreement between equivalent reflections. Rmeas is a multiplicity weighted agreement between equivalent reflections. Avg B gives the average mainchain protein B-factor after refinement.
H418E/Gal was solved in a monoclinic space group (P21) with β = 102.7°. This was crystallized under the same conditions as the other variants, and was refined using CNS with a different geometry library and weighting scheme from the other structures.
The structures of native enzyme (1DP0) and native enzyme with IPTG bound (1JYX) were determined previously. The B-factors are given here for comparison.