Glycoprotein core pentasaccharide

Ratner DM, Swanson ER, Seeberger PH. Automated synthesis of a protected A-linked glycoprotein core pentasaccharide. Org. Lett., 2003 5 4717-4720. 

An intramolecular acetal has also been introduced by the treatment of a mixture of a 1-thio-mannoside, having a methoxybenzyl protecting group at C-2 and an alcohol with DDQ [71] (Scheme 4.4c). Activation of the thioglycoside with methyl triflate gave a P-mannoside as the only anomer. This approach was employed for the synthesis of the core pentasaccharide of N-linked glycoproteins. 

For this purpose, Ag zeolite and Ag, developed by Garegg25 and Paulsen,26 respectively, have been widely employed (Scheme 7.6). Reactions using these activators have found practical use in synthetic studies on glycoprotein glycans and glycolipids. For instance, Paulsen reported the chemical synthesis of the core pentasaccharide structure 6 common to all types of Asn-linked glycans, using the Ag... 

Dan, A. Ito, Y. Ogawa, T., A Convergent and Stereocontrolled Synthetic Route to the Core Pentasaccharide Structure of Asparagine-Linked Glycoproteins. J. Org. 

Solid-phase oligosaccharide synthesis olfers good opportunities for automahon, and using a modihed pephde synthesizer automated oligosaccharide synthesis has been described [114]. As an example of automated ohgosaccharide synthesis, the preparation of the core pentasaccharide of A-hnked glycoproteins (223) is shown in Scheme 5.38 and Scheme 5.39 [115]. 

SCHEME 5.39 Automated solid-phase synthesis of the core pentasaccharide of A-linked glycoproteins. 

Core pentasaccharide Man(a1-6)[Man(a1-3)]Man()J1-4)GlcNAc(/S1-4)GlcNAc of JV-glycoproteins attached to the consensus sequence Asn-Xaa-Ser/Thr. Solid arrows indicate the points of attachment of the outer ami saccharides forming carbohydrate chains, caiied antennae, in addition, the inner-core may be substituted by several monosaccharides dashed arrows)... 

Figure 8.1 Core pentasaccharide structure of V-linked glycoproteins. The dashed box highlights the P-mannoside unit.

Fig. 10 (a) Schematic representation of the core pentasaccharide (in the dashed box) of N-glycans. The green blocks represent the peptide of the glycoprotein and the yellow blocks represent the oligosaccharide assembly that develops from Ssac. (b) The phenyl-tagged core pentasaccharide (Ssac) and the di- and trisaccharide sub-units selected for the gas-phase conformational investigation... 

Natural JV-glycoproteins usually carry a central ( core ) pentasaccharide 41 linked to aspartic add (Scheme 19). 

FIGURE 1. Three major types of Asn-linked saccharide structures found in glycoproteins. The core pentasaccharide is shown boxed in panel a. 

Figure 47-4. Structures of the major types of asparagine-linked oligosaccharides. The boxed area encloses the pentasaccharide core common to all N-linked glycoproteins. (Reproduced, with permission, from Kornfeld R, Kornfeld S Assembly of asparagine-linked oligosaccharides. Annu Rev Biochem 1985 54 631.)...

Figure 47-5. Schematic diagram of the pentasaccharide core common to all N-linked glycoproteins and to which various outer chains of oligosaccharides may be attached. The sites of action of endoglycosidases F and H are also indicated.

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