Separation of Sulfated Fucose-containing Isomers found in L.digitata using Cyclic Ion Mobility Mass Spectrometry
Bibliographic record
Abstract
Brown seaweeds and some marine invertebrates contain bioactive polysaccharides including fucoidan. These biopolymers have antimicrobial, antibacterial, and antifungal properties, and improved characterization of their structures would be valuable as it can correlated with their bioactivity. To our knowledge, fucoidan extracted from the macroalga Laminaria digitata has not been structurally determined. In this paper, we show that both singly and doubly sulfated fucose units, and singly sulfated galactose species present within fucoidan exist as isomers. These were identified via analysis of the biopolymer using Cyclic Ion Mobility Mass Spectrometry (cIM-MS), which has not been used to determine isomeric species present in fucoidan-derived structures previously. Along with using cIM, tandem MS (MS/MS) also provided unique fragmentation related to differing sulfate locations and glycosidic linkages. Along with sulfate location, connectivity positions between both sulfated fucose and galactose trimers and dimers respectively, were identified using Collisional Cross Section (CCS) modelling and drift times from cIM. Previous studies determined that linkage between the sulfated galactose dimer ([Gal2SO3]-) were linked (1→4) due to the presence of m/z = 361. However, differences in both fragmentation and drift time suggest changes in glycosidic linkages between the monomer units [(1→4) versus ((1→3) linkage]. Ions of high m/z were identified such as [Fuc3(SO3)2-H2O]2-, along with smaller, lighter ions such as a dehydrated singly sulfated fucose monomer ([FucSO3-H2O]-) with m/z = 225. Interestingly, a major ion seen in this work appears at m/z = 357, which we hypothesize as a galactose dimer where one unit has ring-opened to yield a deprotonated glycolic acid ion. The presence of this species has not been reported in earlier structural investigations into fucoidan and speaks to the structural complexity of fucoidan present in Laminaria digitata.
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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 | 0.001 | 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".