Insights into the Mechanism of Drosophila melanogaster Golgi α-Mannosidase II through the Structural Analysis of Covalent Reaction Intermediates
Bibliographic record
Abstract
The family 38 golgi alpha-mannosidase II, thought to cleave mannosidic bonds through a double displacement mechanism involving a reaction intermediate, is a clinically important enzyme involved in glycoprotein processing. The structure of three different covalent glycosyl-enzyme intermediates have been determined to 1.2-A resolution for the Golgi alpha-mannosidase II from Drosophila melanogaster by use of fluorinated sugar analogues, both with the wild-type enzyme and a mutant enzyme in which the acid/base catalyst has been removed. All these structures reveal sugar intermediates bound in a distorted 1S5 skew boat conformation. The similarity of this conformation with that of the substrate in the recently determined structure of the Michaelis complex of a beta-mannanase (Ducros, V. M. A., Zechel, D. L., Murshudov, G. N., Gilbert, H. J., Szabo, L., Stoll, D., Withers, S. G., and Davies, G. J. (2002) Angew. Chem. Int. Ed. Engl. 41, 2824-2827) suggests that these disparate enzymes have recruited common stereoelectronic features in evolving their catalytic mechanisms.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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".