Chemoenzymatic synthesis of thio-nod factor intermediates Enzymatic transfer of glucosamine on thiochitobiose derivatives
Bibliographic record
Abstract
The chemoenzymatic syntheses of thioanalogues of nodulation factors in which the nonreducing end glucosamine residue is available for the introduction of the fatty acid moiety at the free NH 2 group are reported. We are describing the chemical synthesis of UDP-GlcNH 2 and its use in the enzymatic transfer of GlcNH 2 by the bovine galactosyltransferase (EC 2.4.1.90) onto O-4 of the nonreducing end N-acetylglucosamine residues of chitobiose, thiochitobiose, and allyl thiochitobioside. The enzymatic reactions on chitobiose and thiochitobiose were followed by TLC and MALDI MS and showed about 50% conversion of the disaccharides to the desired products. However, these reducing trisaccharides could not be obtained totally free of salts and degraded on ion exchange chromatography. Thus, we investigated the enzymatic transfer on the nonreducing allyl thiochitobioside analogue. We describe here the chemical synthesis of this thiodisaccharide and the enzymatic transfer of GlcNH 2 at O-4 of its nonreducing end glucosamine residue to give the desired allyl thiotrisaccharide. This thiotrisaccharide was obtained pure in 41% yield and was characterized by 1 H NMR (HSQC) and HRMS.Key words: nodulation factors, synthesis, enzymatic transfer, thiooligosaccharides, UDP-glucosamine.
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 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) | 0.001 | 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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".