Thiogalactopyranosides are Resistant to Hydrolysis by α‐Galactosidases
Bibliographic record
Abstract
Fluorescently tagged glycosides containing terminal α(1→3) and α(1→4)-linked thiogalactopyranosides have been prepared and tested for resistance to hydrolysis by α-galactosidases. Eight fluorescent glycosides containing either galactose or 5-thiogalactose as the terminal sugar were enzymatically synthesized using galactosyltransferases, with lactosyl glycosides as acceptors and UDP-galactose or UDP-5'-thiogalactose, respectively, as donors. The glycosides were incubated with human α-galactosidase A (CAZy family GH27, a retaining glycosidase), Bacteroides fragilis α-1,3-galactosidase (GH110, an inverting glycosidase), or homogenates of MCF-7 human breast cancer cells or NG108-15 rat glioma cells. Substrate hydrolysis was monitored by capillary electrophoresis with fluorescence detection. All compounds containing terminal O-galactose were readily degraded. Their 5-thiogalactose counterparts were resistant to hydrolysis by human α-galactosidase A and the enzymes present in the cell extracts. B. fragilis α-1,3-galactosidase hydrolyzed both thio- and O-galactoside substrates; however, the thiogalactosides were hydrolyzed at only 1-3 % of the rate of O-galactosides. The hydrolytic resistance of 5-thiogalactose was also confirmed by an in vivo study using cells in culture. The results suggest that 5-thiogalactosides may be useful tools for the study of anabolic pathways in cell extracts or in single cells.
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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) | 0.001 | 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 | 0.000 |
| 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".