Purification, crystallization and preliminary X-ray analysis of the<i>Escherichia coli</i>glucose-1-phosphatase
Bibliographic record
Abstract
Encoded by the agp gene, Escherichia coli glucose-1-phosphatase hydrolyzes glucose-1-phosphate in the periplasmic space of the bacterium. It is a potential drug-design target because inositol phosphatases have been identified as important virulence determinants in several human and animal pathogens. The enzyme was isolated and purified to homogeneity from a strain of E. coli CU1867 (an appA-deficient mutant). Crystals were obtained overnight by the equilibrium vapour-diffusion method from a solution containing 10 mg ml(-1) enzyme, 1.2 M ammonium sulfate and 25% polyethylene glycol monomethyl ether 5000 in 0.1 M MES at pH 6.5. The crystals belong to space group R3, with unit-cell parameters a = b = 156.0, c = 92.2 A. The diffraction limit was 2.6 A at a rotating-anode X-ray source; a 2.7 A resolution data set has been collected using light mineral oil as a cryoprotectant. The data set was 95.2% complete, with an R(sym) of 0.058. There were two monomers of glucose-1-phosphatase in the asymmetric unit, which correspond to a V(M) of 2.36 A Da(-1) and 47.5% solvent content. Self-rotation analysis unambiguously shows a twofold non-crystallographic symmetry.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".