Crystallization and preliminary X-ray analysis of (1<i>R</i>,6<i>R</i>)-2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate (SHCHC) synthase (MenD) from<i>Escherichia coli</i>
Why this work is in the frame
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Bibliographic record
Abstract
(1R,6R)-2-Succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate (SHCHC) synthase, also called MenD, participates in the menaquinone (vitamin K2) biosynthetic pathway. The enzyme is a part of the superfamily of ThDP-dependent enzymes; however, it is the only enzyme known to catalyze a Stetter-like 1,4-addition of a ThDP adduct to the beta-carbon of an unsaturated carboxylate. This is the first reported crystallization of the apoenzyme and holoenzyme forms of MenD. The apoenzyme crystals were obtained by sitting-drop vapour diffusion with 70% MPD. However, the crystals were too small to collect diffraction data and a search for better conditions was not successful. Single crystals of the holoenzyme with ThDP and Mn2+ as cofactors were obtained by the hanging-drop vapour-diffusion method with 35% ethylene glycol as precipitant. Diffraction data were collected on a cryocooled crystal to a resolution of 2.0 A at BioCARS, Advanced Photon Source (APS), Chicago, IL, USA. The crystal was found to belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 106.86, b = 143.06, c = 156.85 A, alpha = beta = gamma = 90 degrees.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 it