Identification of the two essential groups in the family 3 β-glucosidase from Flavobacterium meningosepticum by labelling and tandem mass spectrometric analysis
Why this work is in the frame
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Bibliographic record
Abstract
beta-Glucosidase from Flavobacterium meningosepticum (Fbgl) catalyses the hydrolysis of beta-1,4-glucosidic bonds via a two-step double-displacement mechanism in which two amino acid residues act as nucleophile and acid/base catalyst. Definitive identification of these two residues is provided by the two active-site-directed inactivators, 2',4'-dinitrophenyl-2-deoxy-2-fluoro-beta-d-glucoside (2FDNPG) and N-bromoacetyl-beta-d-glucosylamine (NBGN), which stoichiometrically label the nucleophile and the acid/base catalyst of Fbgl, respectively. Pseudo-first-order inactivation rate constants (k(i)) of 0.25+/-0.01 and 0.05+/-0.01 min(-1) and dissociation constants (K(i)) of 90+/-15 and 4.4+/-0.2 mM are determined for 2FDNPG and NBGN, respectively. Proteolytic digestion of the labelled proteins, followed by peptide mapping and tandem MS analysis identify Asp-247 and Glu-473 as the catalytic nucleophile and acid/base residues, respectively, of Fbgl. This study confirms that the catalytic nucleophile of family 3 glycohydrolase is conserved across sub-families. However, different sub-families may have unique general acid/base catalysts.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| 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