Expression and Characterization of Glycosyl Hydrolase Family 115 α-Glucuronidase from <i>Scheffersomyces stipitis</i>
Bibliographic record
Abstract
The gene encoding glycosyl hydrolase family 115 α-glucuronidase from Scheffersomyces stipitis (ssagu115) was cloned and expressed in Pichia pastoris strain X33. The recombinant enzyme was purified to homogeneity by Ni-chelation affinity chromatography. The apparent molecular weight of the secreted recombinant enzyme was about 150 kDa as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The recombinant α-glucuronidase was able to remove 4-O-methylglucuronic acid groups from several polymeric xylans (beech, birch, and oat spelt xylan) as well as xylooligosaccharides (aldotetraouronic acid and aldopentaouronic acid). The enzyme was more active towards xylooligosaccharides than xylans. Substrate inhibition was observed with aldouronic acids at concentrations above 23 mM. The Km values of the enzyme towards aldotetraouronic and aldopentaouronic acids were 8.2 mM (5 mg/mL) and 9 mM (6.5 mg/mL), respectively. For beech and birch xylan, the Km values were 9.5 mg/mL and 35 mg/mL, respectively. The enzyme was active over the pH range of 3.0–8.5, with maximal activity at pH 4.0. The optimum temperature for activity of the enzyme was 50°C. The enzyme exhibited synergy with endoxylanases from the GH10 and GH11 families on hydrolysis of beech xylan, birch xylan, and oat spelt xylan, with the greatest synergistic effect being shown with the GH10 endoxylanase. Treatment of polymeric xylan with SsAgu115 led to reduced solubility and increased precipitation from solution. Insoluble xylans have the potential to form hydrogels, which may have pharmaceutical and biomedical applications.
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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 | 0.000 |
| 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".