A novel alcohol dehydrogenase in the hyperthermophilic crenarchaeon <i>Hyperthermus butylicus</i>
Bibliographic record
Abstract
Abstract Hyperthermus butylicus is a hyperthermophilic crenarchaeon that produces 1‐butanol as an end product. A thermostable alcohol dehydrogenase (ADH) must be present in H. butylicus to act as the key enzyme responsible for this production; however, the gene that encodes the ADH has not yet been identified. A novel ADH, HbADH2, was purified from a cell‐free extract of H. butylicus , and its characteristics were determined. The gene that encodes HbADH2 was demonstrated to be HBUT_RS04850 and annotated as a hypothetical protein in H. butylicus . HbADH2 was found to be a primary–secondary ADH capable of using a wide range of substrates, including butyraldehyde and butanol. Butyraldehyde had the highest specificity constant, calculated as k c at / K m , with k cat and apparent K m values of 8.00 ± 0.22 s −1 and 0.59 ± 0.07 mM, respectively. The apparent K m values for other substrates, including ethanol, 1‐propanol, 2‐propanol, butanol, acetaldehyde, propanal, and acetone, were 4.36 ± 0.42, 4.69 ± 0.41, 3.74 ± 0.46, 2.44 ± 0.30, 1.27 ± 0.18, 1.55 ± 0.20, and 0.68 ± 0.04 mM, respectively. The optimal pH values for catalyzing aldehyde reduction and alcohol oxidation were 6.0 and 9.0, respectively, while the optimal temperature was higher than 90°C due to the increase in enzymatic activity from 60°C to 90°C. Based on its substrate specificity, enzyme kinetics, and thermostability, HbADH2 may be the ADH that catalyzes the production of 1‐butanol in H. butylicus . The putative conserved motif sites for NAD(P) + and iron binding were identified by aligning HbADH2 with previously characterized Fe‐containing ADHs.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".