Home > Products > Glycoscience > TOPICS > Sialylglycopeptide (SGP), Disialyloctasaccharide

Sialylglycopeptide (SGP), Disialyloctasaccharide

Sialylglycopeptide (SGP) : Glycopeptide containing sialic acids at non-reducing terminal (11 sugar constituents)


Disialyloctasaccharide : Oligosaccharide containing sialic acids at non-reducing terminal (10 sugar constituents)


• By cost-cutting with large-scale production, the price of these items were discounted!

• We hope you will find these structure-defined oligosaccharides useful.

• Please contact us about a request of several hundred grams-scale production.

Page Top

Biosynthesis and N-glycan

 Oligosaccharide attachment during post-translational modification in protein biosynthesis is a ubiquitous biological process. While N-linked oligosaccharides are found in various eukaryotes, their oligosaccharide structures are of great diversity and heterogeneity between different organisms.1) Unfortunately, this heterogeneity is difficult to be homogenized in vivo and glycosylation of biopharmaceuticals remains a challenging problem to resolve.

Page Top

Function of human-type N-glycan

Sialylated N-glycan is a typical human-type glycan that is suggested to be strongly correlated with various physiological phenomena:

 • Viral infection (by human influenzae, etc.)2)

 • Delayed blood glycoprotein half-life (owing to hindered clearance by the hepatic asialoglycoprotein receptor)3)

 • Anti-inflammatory activity with sialylated N-glycan of the IgG Fc region (via endogenous immune-receptors such as DC-SIGN, etc.)4)

 • Immunoregulation caused by endogenous lectins (such as Siglecs which preferentially bind to sialylated oligosaccharides)5)

 • Relevance to stability of biopharmaceuticals (e.g. erythropoietin: EPO)6)

Sialylated N-glycan may contribute to various applications:

 • Improvement of biophamaceutical function (via oligosaccharide remodeling)

 • Virus scavenger (based on a matrix of conjugated oligosaccharides)

 • Drug delivery systems (as an oligosaccharide-immobilized DDS)

 • Oligosaccharide analysis of biological specimens and biophamaceuticals (internal or externalstandard)

 • Stabilization of proteins (improved solubility)

 • General Glycoscience (glycosidase, competitive inhibitors and etc.)

Page Top

Practical example: Oligosaccharide remodeling of N-glycan on antibody with 2 types of oligosaccharide donors and Endo-M related enzymes

A. Structure-defined oligosaccharide donor

 By chemoenzymatic glycoengineering with Endo-M and Glycosynthase, heterogenous N-linked oligosaccharides attached to an antibody are replaced by fine-defined, an oligosaccharide with focused substrate specificity toward non-corefucosylated biantennary N-glycan.7)
 First, Endo-M hydrolyses a glycoside-bond of chitobioses linked to N-glycan of IgG via an oxazoline intermediate, which subsequently exposes the innermost GlcNAc residue. Next, Glycosynthase bearing a point-mutation on Endo-M performs transglycosylation targeting the GlcNAc residue. The oligosaccharide donors, not only the activated Disialyloctasaccharide with oxazoline formation8) but also the Sialylglycopeptide (SGP), are available to the oligosaccharide remodeling.9)
(The reaction for oligosaccharide remodeling toward IgG with Endo-M and Glycosynthase is conducted under non-reducing conditions, whereas the analysis is performed under reducing conditions with denaturing.)

Structure-defined oligosaccharide donor

Page Top

B. Verification of oligosaccharide replacement with a non-fucosylated N-glycan attached to a heavy chain of antibody via capillary electrophoresis

 Following the hydrolysis reaction for an N-glycan attached antibody (IgG) by Endo-M, the size reduction of the heavy chain can be verified via capillary electrophoresis (Blue line).
Next, the coupling between two types of sialylated oligosaccharide donors and a GlcNAc residue remaining on the antibody is conducted by Glycosynthase. Using an activated oxazoline donor derived from an oxazolinated Disialyloctasaccharide, would result in high reactivity. However, non-specific additional incorporation of an oxazoline-activated Disialyloctasaccharide onto any amino acid residue can be observed (Red line left). Alternatively, the non-specific incorporation of oligosaccharides is not found with SGP donors (Red line right).
Finally, after the coupling of a uniform oligosaccharide to the GlcNAc-exposed antibody, a peak shift in the heavy chain is observed whereas it is not for the light chain.

Verification of oligosaccharide replacement

Page Top

C. Verification of the heavy chain size by SDS-PAGE

 Size reduction of the heavy chain is observed when an N-glycan attached to the heavy chain is hydrolyzed by Endo-M treatment. With regards to transglycosylation by Glycosynthase, two types of sialylated donors resulted in a larger molecular size compared with original IgG from capillary electrophoresis. A peak shift of the heavy chain is observed but not the light chain.

Verification of a molecular size of the heavy chain by SDS-PAGE

Page Top

D. Detecting incorporation of sialylated oligosaccharides into Endo-M-treated antibody by lectin-blotting

 Incorporation of the sialylated oligosaccharide is validated by lectin-blotting with a sialic acid-binding lectin (SSA: Sambucus sieboldiana agglutinin). Only the heavy chain of the transglycosylated antibody aappears to exhibit susceptibility to SSA.

Detecting incorporation of sialylated oligosaccharides

Page Top