Crystal Structure of Thermotoga maritima α-l-Fucosidase
Bibliographic record
Abstract
Fucosylated glycoconjugates are involved in numerous biological events, and alpha-l-fucosidases, the enzymes responsible for their processing, are therefore of crucial importance. Deficiency in alpha-l-fucosidase activity is associated with fucosidosis, a lysosomal storage disorder characterized by rapid neurodegeneration, resulting in severe mental and motor deterioration. To gain insight into alpha-l-fucosidase function at the molecular level, we have determined the crystal structure of Thermotoga maritima alpha-l-fucosidase. This enzyme assembles as a hexamer and displays a two-domain fold, composed of a catalytic (beta/alpha)(8)-like domain and a C-terminal beta-sandwich domain. The structures of an enzyme-product complex and of a covalent glycosyl-enzyme intermediate, coupled with kinetic and mutagenesis studies, allowed us to identify the catalytic nucleophile, Asp(244), and the Brønsted acid/base, Glu(266). Because T. maritima alpha-l-fucosidase occupies a unique evolutionary position, being far more closely related to the mammalian enzymes than to any other prokaryotic homolog, a structural model of the human enzyme was built to document the structural consequences of the genetic mutations associated with fucosidosis.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".