Notes

Oligosaccharides Reduction Number Peaks Acids Subfractionation Structure
The microcarrier process resulted in a reduced amount of sialylated oligosaccharide species as compared to the suspension cell process. 2'-fucosyllactose of sialic acid followed by chromatography of the asialooligosaccharides under high pH anion-exchange conditions indicated that the same antennary structures were present but in slightly different relative amounts. The oligosaccharide profiles are indicative of a highly complex array of microheterogeneity present, encompassing mono-, di-, tri-, and tetrasialylated complex type Synthesis of 1,3-di-O-alkyl-2-O-(beta-glycosyl)glycerols bearing oligosaccharides as hydrophilic groups.A novel series of synthetic glycolipids, 1,3-di-O-alkyl-2-O-(beta-glycosyl)glycerols, and their efficient synthetic route were proposed. These glyceroglycolipids were synthesized in good overall yields and stereoselectivity in five steps via trichloroacetimidate glycosylation with 1,3-di-O-alkylglycerols. This route was applied to prepare the glycolipids bearing a cello- or malto-oligosaccharide with a definite number of sugar residues from one to six.

Thin-layer chromatography, elemental analysis, nuclear magnetic resonance spectroscopy and infrared absorption spectroscopy confirmed that these glycolipids were chemically pure compounds.Characterization and analysis of branched-chain N-acetylglucosaminyl oligosaccharides accumulating in Sandhoff disease tissue. Evidence that biantennary bisected oligosaccharide side chains of glycoproteins are abundant Branched chain N-acetylglucosaminyl oligosaccharides accumulating in visceral and neural tissues of two patients with Sandhoff disease were isolated and quantified using high performance liquid chromatography. Detailed structural analysis of the three most abundant fractions, oligosaccharides 4, 5, and 6, was carried out using 3 MHz proton magnetic resonance spectroscopy. The biantennary bisected heptasaccharide, oligosaccharide 6, was ubiquitously distributed and a major component of the stored oligosaccharides in all tissues analyzed including, liver, spleen, kidney, lung, pancreas, and brain. This analysis indicates that glycoproteins containing biantennary bisected oligosaccharide side chains are abundant substrates for lysosomes in human tissues. Moreover, oligosaccharide 6 was the predominant storage product in brain comprising % of the total accumulating water-soluble glycoconjugates.

Oligosaccharide 5, a triantennary heptasaccharide, had a similar distribution in visceral tissues and it was the major storage product in pancreas but was at very low levels in brain. These results suggest that the biosynthetic enzymes, GlcNAc transferase III (Narasimham, S. (1982) J. Biol. Chem. 257, 235-242) and IV (Gleeson, P.A.

, and Schachter, H. (1983) J. Biol. Chem. 258, 6162-6173), which are responsible for synthesis of these structures, have a generalized distribution with varying levels of expression in human viscera, moreover, transferase IV may have limited expression in neural tissue. The proposed structures for the branched-chain compounds are as follows. (formula; see text)Previously, we communicated 3,3-difluoroxindole (HOFox)-mediated glycosylations wherein 3,3-difluoro-3H-indol-2-yl (OFox) imidates were found to be key intermediates.

Both the in situ synthesis from the corresponding glycosyl bromides and activation of the OFox imidates could be conducted in a regenerative fashion. Herein, we extend this study to the synthesis of various glycosidic linkages using different sugar series. The main outcome of this study relates to enhanced yields andor reduced reaction times of glycosylations. 2'-FL of HOFox-mediated reactions is particularly pronounced in case of unreactive glycosyl donors andor glycosyl acceptors. A multistep regenerative synthesis of oligosaccharides is also reported.Conflict of interest statement Notes The authors declare no competing financial Pivalates in the selective protection and activation of maltose for the synthesis of sulfated 3-deoxy-maltosyl-(1--4)-alpha, alpha-trehalose.Pivaloylation of maltose gave, in satisfactory yield, 1,2,6,2',3',4',6'-hepta-O-pivaloyl-beta-maltose which was converted to the 3-deoxygenated analogue in a Barton-McCombie reaction.

This compound was used directly in a trimethylsilyl triflate-mediated glycosylation reaction with 2,3,6-tri-O-benzyl-alpha-D-glucopyranosyl 2,3-di-O-benzyl-4,6-O-benzylidene-alpha-D-glucopyranoside to give the corresponding maltosyl-(1--4)-alpha, alpha-trehalose derivative. After deprotection, the monodeoxygenated tetrasaccharide was sulfated; in the reaction product, one compound fully sulfated at the outer pyranose rings predominated.
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