Synthesis of a Candida albicans tetrasaccharide spanning the β1,2-mannan phosphodiester α-mannan junction
Bibliographic record
Abstract
The cell wall phosphomannan of Candida species is a complex N-linked glycoprotein with a glycan chain containing predominantly an α-linked mannose backbone with α-mannose branches. A minor β-mannan component is attached to the branches either via a glycosidic bond (acid stable β-mannan) or a phosphodiester bond (acid-labile β-mannan). The α-mannan residues of the cell wall phosphomannan do not afford protective antibody, while the β-mannan portion is a protective antigen and has become an attractive target as the key epitope of a conjugate vaccine. We report the first synthesis of a tetrasaccharide 1 consisting of a β1,2-mannopyranosyl trisaccharide linked via a phosphodiester to methyl α-mannopyranoside. This encompasses the attachment site of the acid labile β-mannan to the α-mannan component of the cell wall phosphomannan. The trisaccharide was formed by an iterative process to first create a β-glucopyranoside linkage and then epimerize the C-2 center via an oxidation-reduction sequence. The phosphate diester linkage was accessed via an anomeric H-phosphonate. The binding of phosphomannan fragment 1 with the protective antibody C3.1 has been evaluated and compared with a β-mannotrioside in hapten inhibition experiments. The observed activities are rationalized with a model for docked in the binding site of C3.1.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 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 teacher head, 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".