Discovery of a Fungal Copper Radical Oxidase with High Catalytic Efficiency toward 5-Hydroxymethylfurfural and Benzyl Alcohols for Bioprocessing
Bibliographic record
Abstract
Alternatives to petroleum-based chemicals are highly sought-after for ongoing efforts to reduce the damaging effects of human activity on the environment. Copper radical oxidases from Auxiliary Activity Family 5/Subfamily 2 (AA5_2) are attractive biocatalysts because they oxidize primary alcohols in a chemoselective manner without complex organic cofactors. However, despite numerous studies on canonical galactose oxidases (GalOx, EC 1.1.3.9) and engineered variants, and the recent discovery of a Colletotrichum graminicola copper radical alcohol oxidase (AlcOx, EC 1.1.3.13), the catalytic potentials of very few AA5_2 members have been characterized. Guided by the sequence similarity network and phylogenetic analyses, we targeted a distinct paralog from the fungus C. graminicola as a representative member of a large uncharacterized subgroup of AA5_2. Through recombinant production and detailed kinetic analysis, we demonstrated that this enzyme is weakly active toward carbohydrates but efficiently catalyzes the oxidation of aryl alcohols to the corresponding aldehydes. As such, this represents the initial characterization of a demonstrable aryl alcohol oxidase (AAO, EC 1.1.3.7) in AA5, an activity which is classically associated with flavin-dependent glucose-methanol-choline (GMC) oxidoreductases of Auxiliary Activity Family 3 (AA3). X-ray crystallography revealed a distinct multidomain architecture comprising an N-terminal PAN domain abutting a canonical AA5 seven-bladed propeller catalytic domain. Of direct relevance to biomass processing, the wild-type enzyme exhibits the highest activity on the primary alcohol of 5-hydroxymethylfurfural (HMF), a product of significant interest in the lignocellulosic biorefinery concept. Thus, the chemoselective oxidation of HMF to 2,5-diformylfuran (DFF) by C. graminicola aryl alcohol oxidase ( Cgr AAO) from AA5 provides a fundamental building block for chemistry via biotechnology.
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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".