Efficient Preparation of Natural and Synthetic Galactosides with a Recombinant β-1,4-Galactosyltransferase-/UDP-4‘-Gal Epimerase Fusion Protein
Bibliographic record
Abstract
The numerous biological roles of LacNAc-based oligosaccharides have led to an increased demand for these structures for biological studies. In this report, an efficient route for the synthesis of beta-galactosides using a bacterial beta-4-galactosyltransferase/-UDP-4'-gal-epimerase fusion protein is described. The lgtB gene from Neisseria meningitidis and the galE gene from Streptococcus thermophilus were fused and cloned into an expression vector pCW. The fusion protein transfers galactose to a variety of different glucose- and glucosamine-containing acceptors, and utilizes either UDP-galactose or UDP-glucose as donor substrates. A crude lysate from Escherichia coli expressing the fusion protein is demonstrated to be sufficient for the efficient preparation of galactosylated oligosaccharides from inexpensive UDP-glucose in a multigram scale. Lysates containing the fusion protein are also found to be useful in the production of more complex oligosaccharides in coupled reaction mixtures, e.g., in the preparation of sialosides from N-acetylglucosamine. Thus, bacterially expressed fusion protein is well suited for the facile and economic preparation of natural oligosaccharides and synthetic derivatives based on the lactosamine core.
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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 | 0.000 | 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".