Notes

Chemical Treatments Structure Man Man Alpha Man Alpha Man Alpha Man Alpha Man Oligosaccharides Proteins Treatment Protease H
One of the protein-bound oligosaccharides had the same structure as the lipid-linked compound, whereas in the second oligosaccharide some mannose residues had been replaced by galactose units, but both compounds migrated as did a Man7GlcNAc standard. These were the largest oligosaccharides obtained even after short labeling periods. It is suggested that glycosylation of proteins in the protozoan Crithidia fasciculata does not involved glucosylated lipid-bound oligosaccharides as intermediates.Preparation of Defined Chitosan Oligosaccharides Using Chitin Deacetylases.During the past decade, detailed studies using well-defined 'second generation' chitosans have amply proved that both their material properties and their biological activities are dependent on their molecular structure, in particular on their degree of polymerisation (DP) and their fraction of acetylation (FA). Recent evidence suggests that the pattern of acetylation (PA), i.

e., the sequence of acetylated and non-acetylated residues along the linear polymer, is equally important, but chitosan polymers with defined, non-random PA are not yet available. One way in which the PA will influence the bioactivities of chitosan polymers is their enzymatic degradation by sequence-dependent chitosan hydrolases present in the target tissues. The PA of the polymer substrates in conjunction with the subsite preferences of the hydrolases determine the type of oligomeric products and the kinetics of their production and further degradation. Thus, the bioactivities of chitosan polymers will at least in part be carried by the chitosan oligomers produced from them, possibly through their interaction with pattern recognition receptors in target cells. In contrast to polymers, partially acetylated chitosan oligosaccharides (paCOS) can be fully characterised concerning their DP, FA, and PA, and chitin deacetylases (CDAs) with different and known regio-selectivities are currently emerging as efficient tools to produce fully defined paCOS in quantities sufficient to probe their bioactivities. In this review, we describe the current state of the art on how CDAs can be used in forward and reverse mode to produce all of the possible paCOS dimers, trimers, and tetramers, most of the pentamers and many of the hexamers.

In addition, we describe the biotechnological production of the required fully acetylated and fully deacetylated oligomer substrates, as well as the purification and characterisation of the paCOS products.Conflict of interest statement The authors declare no conflict of interest.The absorption of bovine milk small extracellular vesicles largely depends on galectin 3 and galactose ligands in human intestinal cells and C57BL6J mice.Small extracellular vesicles in milk (sMEVs) have attracted attention in drug delivery and as bioactive food compounds. Fucosylated Lactose implicate galactose residues on the sMEV surface in sMEV transport across intestinal and endothelial barriers in humans, but details of glycoprotein-dependent transport are unknown. We used a combination of cell biology and genetics protocols to identify glycoproteins on the sMEV surface that facilitate sMEV absorption. We identified 256 proteins on the bovine sMEVs surface by using LC-MSMS, and bioinformatics analysis suggested that 42, 13, and 13 surface proteins were N-, O-, and 13 C-glycosylated, respectively.

Lectin blots confirmed the presence of mannose, galactose, N-acetyl galactose, fucose, and neuraminate. When surface proteins were removed by various treatment with various proteases, sMEV uptake decreased by up to 58% and 67% in FHs-74 Int and Caco-2 cells, respectively, compared with controls (P 5). When lacto-n-neotetraose were removed by treatment with various glycosidases, sMEV uptake decreased by up to 54% and 74% in FHs-74 Int and Caco-2 cells, respectively (P 5). When galactose and N-acetyl galactosamine residues were blocked with agglutinins, sMEV uptake decreased by more than % in FHs-74 Int cells (P 5). When bovine sMEVs were administered to Galectin-3 knockout mice by oral gavage, hepatic sMEV accumulation decreased by 56% compared with wild-type mice (P 5), consistent with a role of β-galactoside glycan structures in the absorption of sMEVs. We conclude that sMEVs are decorated with glycoproteins, and Galectin-3 and its galactose ligands are particularly important for sMEV absorption.NEW & NOTEWORTHY This is the first paper to assess the role of unique glycans and their Galectin-3 receptor in the transport and distribution of small extracellular vesicles (exosomes) from milk in mammals.
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