Purification and biochemical characterization of a cyclodextrin glycosyltransferase from <i>Geobacillus thermoglucosidans</i> CHB1
Bibliographic record
Abstract
A strain named Geobacillus thermoglucosidans CHB1 was isolated from stockpiled hen dung compost. The cyclodextrin glycosyltransferase (CGTase) from the fermentation broth of this microorganism was purified 350.50‐fold at a yield of 9.33% through ammonium sulfate precipitation, DEAE‐Sepharose Fast Flow chromatography, Sephadex G‐100 chromatography, and preparative electrophoresis. Sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) revealed that the molecular mass of the purified enzyme was approximately 70 kDa. The CGTase maintained more than 50% cyclization activity between 50 and 80°C and optimal activity at 65–70°C and remained stable at 50°C. Its optimal pH was 5.5, and its activity showed stability between pH 5.5 and 9.5. The activity of the enzyme was significantly enhanced by LiCl, NiCl2, and MgSO4 but inhibited by AlCl3, CoCl2, FeCl3, HgCl2, BaCl2, SDS, and ZnSO4. The Km and Vmax of the reaction of this enzyme with soluble starch as the substrate were 12.5 mg/mL and 23.7 μmol/min, respectively. This enzyme produced α‐cyclodextrin (CD), β‐CD, and γ‐CD at a ratio of 0.57:1:0.21 from soluble starch as the substrate, and the conversion rate reached 60.3% from 3% soluble starch within 21 h. This CGTase also produced CDs from maltodextrin and potato starch as the substrate. To the best of our knowledge, this manuscript constitutes the first report of a CGTase purified from G. thermoglucosidans, and the results show that this enzyme might have potential for use in industrial production processes requiring stable thermal conditions, but further work is required to optimize its affinity and activation conditions.
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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) | 0.000 | 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".