Nanomolar versus Millimolar Inhibition by Xylobiose-Derived Azasugars: Significant Differences between Two Structurally Distinct Xylanases
Bibliographic record
Abstract
The synthesis of xylobiose-derived nitrogen-containing inhibitors of xylanase is described starting with accessible precursors through efficient synthetic schemes. Four disaccharides were identified as powerful competitive inhibitors of the retaining family 10 xylanase, Cex, from Cellulomonas fimi, namely imidazole ( K i = 150 nM), lactam oxime ( K i = 370 nM), isofagomine ( K i = 130 nM), and deoxynojirimycin ( K i = 5800 nM) derivatives of xylobiose. By contrast, none of the compounds inhibited the family 11 xylanase, Bcx, from Bacillus circulans, to an appreciable extent. Two possible explanations are provided for the discrimination exhibited by the imidazole and the lactam oxime. One explanation relates to the different active site locations of the acid/base residue in the two enzymes: anti to the C1−O5 bond for the family 10 Cex and syn for the family 11 Bcx. The other explanation concerns proposed differences in the transition state conformation for the two enzymes: half-chair for Cex and boat for Bcx. The reasons for the difference in inhibition values between Cex and Bcx for the isofagomine and deoxynojirimycin derivatives are less clear-cut but may be ascribed to destabilizing steric and electrostatic interactions between the inhibitors and an essential tyrosine residue in the active site of Bcx.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
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 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| 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 teacher head, 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".