Artikel
Characterization of the molecular structure of fucoidans using size-exclusion chromatography with multiple detection
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Veröffentlicht: | 7. Oktober 2020 |
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Gliederung
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Fucoidans represent an intriguing class of marine sulfated polysaccharides (SP) with multiple bioactivities. Their activities are dependent on their structural parameters including molecular weight (MW), degree and pattern of sulfation, monosaccharide composition, as well as degree and type of chain branching of these SP. While modern NMR and mass spectrometry techniques allow elucidating details of primary structure, the knowledge about the structure of whole fucoidan molecules and especially their three-dimensional structure is still limited. In the case of SP, the latter may be more important for their interactions with target biostructures than the primary structure of fragments.
Contrary to traditional MW determination by SEC with conventional calibration, SEC with multiple detection provides the absolute molecular weight and simultaneously enables characterization of polymeric architecture. Here, this method was used to compare fucoidans extracted from the brown algae Fucus evanescens, Laminaria digitata and Saccharina latissimi, concerning their MW and size distribution, polydispersity, chain conformation in PBS solution and branching topology. Further, the native fucoidans were degraded to medium- and low-MW fucoidans, using H2O2 and subsequently examined for architectural changes due to degradation.
The native fucoidans displayed considerable structural diversity including large differences in their MW profiles and were heterogeneously composed. Most of the fucoidan fractions turned out to exist as expanded flexible chains. The conformation data suggest that the sulfated polysaccharide molecules have branched structures with partly long side chains. Degradation reduced the polydispersity as well as the heterogeneity of composition. Consequently, degraded fucoidans primarily consisted of expanded flexible chains.
In conclusion, SEC with multiple detection proved to provide additional information about the structure of fucoidans being valuable for the interpretation of bioactivity differences between various fucoidans.