Examination of the structural basis for O(H) blood group specificity by <i>Ulex europaeus</i> Lectin I
Bibliographic record
Abstract
The structural basis for carbohydrate specificity of the first lectin from Ulex europaeus (UE-I) is reported. UE-I is a dimeric metalloglycoprotein that binds the H-type 2 human blood group determinant (α-L-Fucα(1[Formula: see text]2)-β;-D-Galβ(1[Formula: see text]4)-β-D-GlcNAcα-), the blood group determinant present on the surface of O-type erythrocytes. The structural characteristics of UE-I involved in carbohydrate recognition have been examined using mass spectrometry (MS) and X-ray diffraction analysis. MS analysis allowed for discrimination between the different primary structures reported for UE-I. To examine the binding of the H-type 2 blood group determinant by UE-I, the methyl glycosides of the fucose monosaccharide (α-L-Fuc-OMe), known to exhibit primary binding specificity, and the H-type 2 trisaccharide (H-type 2-OMe) were, in two separate experiments, co-crystallized into the binding site of UE-I. The UE-I:α-L-Fuc-OMe complex crystallizes in the monoclinic space group P21, with unit cell dimensions a = 71.81, b = 69.00, and c = 119.02 Å, and β = 106.76°. Two UE-I dimers are observed to be present within the asymmetric unit, and the model has been refined to a R-value and RFree of 0.202 and 0.289, respectively, to 2.3 Å resolution. The preliminary model of the UE-I:H-type 2-OMe complex has been refined at 3.0 Å resolution. The UE-I:H-type 2-OMe complex crystallizes in the orthorhombic space group C2221, with unit cell dimensions a = 88.80, b = 164.75, and c = 77.42 Å, and a single UE-I dimer is present within the asymmetric unit. The carbohydrate recognition domain of UE-I has been identified to be comprised of residues Glu44, Thr86, Asp87, Arg102, Ala103, Gly104, Gly105, Tyr106, Ile129, Val133, Asn134, Trp136, Tyr219, and Arg222. Several critical protein-carbohydrate interactions have been identified, including the role of the hydrophobic interaction between the Thr86 side chain and C-5-CH3 of the α-L-Fuc-OMe. The role of these interactions in carbohydrate recognition-binding by UE-I, as well as differences between the observed and previously modeled complexes, are discussed. Key words: Ulex europaeus lectin I, H-type 2 human blood group determinant, protein-carbohydrate interactions, X-ray crystallography, chemical mapping.
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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".