Structural analysis of a bacterial exo- -D-N-acetylglucosaminidase in complex with an unusual disaccharide found in class III mucin
Bibliographic record
Abstract
CpGH89 is a family 89 glycoside hydrolase with exo-α-D-N-acetylglucosaminidase activity that is produced by the human and animal pathogen Clostridium perfringens. This enzyme is active on the α-D-GlcpNAc-(1 → 4)-D-Galp motif that is displayed on the class III mucins within the gastric mucosa. Other members of this enzyme family, such as human NAGLU, are active on heparan. A truncated version of CpGH89 was rendered inactive through the mutation of two key catalytic residues, the protein crystallized and its structure determined in complex with α-D-GlcpNAc-(1 → 4)-D-Galp to reveal the molecular details of how this unique disaccharide is recognized by CpGH89. An analysis of this substrate complex not only provides insight into how this enzyme selects for its mucin-presented substrate but also advances our understanding of how its clinically relevant mammalian counterparts are specific for heparan.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".