The biosynthesis and regulation of biosynthesis of Concord grape fruit esters, including ‘foxy’ methylanthranilate
Bibliographic record
Abstract
The biosynthesis of methyl anthranilate, the volatile compound responsible for the distinctive 'foxy' aroma and flavor of the Washington Concord grape (Vitis labrusca), involves an alcohol acyltransferase that catalyzes the formation of methyl anthranilate from anthraniloyl-coenzyme A (CoA) and methanol. Although methanol is a poor substrate in comparison with the co-substrate, high levels of this acyltransferase (0.5% of the total protein) combined with relatively high levels of this alcohol make this reaction possible in grapes. This 449 amino acid protein belongs to the BAHD family of acyltransferases, having 58% identity with the benzoyl CoA:benzyl alcohol benzoyl transferase from Clarkia. Both native and recombinant enzymes can use a broad range of acyl-CoAs and alcohols as substrates. The ability of Concord grape alcohol acyltransferase to accept a range of different CoA esters and alcohols suggests this to be a versatile ester-forming enzyme, similar to those of other fruits that than can produce a range of fruit esters based on the supply of appropriate substrates. Expression is coordinately regulated, with transcript, protein and enzyme activities coinciding with the accumulation of methyl anthranilate that occurs after the initiation of berry ripening. The majority of acyltransferase protein in grape tissues is localized to the outer fruit mesocarp, a result consistent with the fact that methyl anthranilate is released to the external environment throughout the ripening process. Wine grapes (Vitis vinifera) that accumulate neither anthranilate nor methyl anthranilate do not express this enzyme activity nor do they accumulate this protein.
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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 | 0.001 | 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".