Sialylated tetrasaccharide

Savage, A.V., Donohue, J.J., Koeleman, C.A.M. and van den Eijnden, D.H. (1990) Structural characterization of sialylated tetrasaccharides and pentasaccharides with blood-group H and Lex activity isolated from bovine submaxillary mucin. European Journal of Biochemistry 193, 837-843. 

Kmsius T, Finne J, Margohs RK, Margohs RU. Identification of an 0-glycosidic mannose-linked sialylated tetrasaccharide and keratan sulfate oligosaccharides in the chondroitin sulfate proteoglycan of brain. J. Biol. Chem. 1986 261(18) 8237-8242. 

In the second approach, treatment of lactoside derivatives 19 and 63 with benzaldehyde dimethylacetal in dry acetonitrile using p-toluenesulfonic acid as catalyst gave the 4, 6 -0-benzylidene derivatives 66 and 67 in 93% and 89% yield, respectively. Further derivatization of 23 (Scheme 4) was also considered in order to prepare sialyl Le as shown in Scheme 15. The disarmed-latent trisaccharide acceptor 23 was first coupled with ethylthio fucopyranosyl donor 57 in the presence of NIS/TfOH in dichloromethane at —70°C to give sialylated tetrasaccharide 70 in 63% yield together with recovered trisaccharide acceptor 23 (17%) and a minor unidentified regioisomer (less than 10%) (Scheme 15). 

Fluorogenic compound (56) for transketolase assays has been prepared making use of FruA specificity [123]. Pendant anionically charged chains have been extended from O- or C-glycosidic aldehydes to furnish low molecular weight mimics of the sialyl Lewis X tetrasaccharide such as (SS) (Figure 10.23) [124], Other higher carbon... 

Scheme 8.1 Synthesis of a sialyl-Lewis tetrasaccharide employing C-enriched protecting groups for the quantitative reaction monitoring using gated decoupling NMR spectroscopy.

N-Glycopeptides Carrying the Sialyl Lewis A Structure The regioisomeric tetrasaccharide structures sialyl Lewis A (sLea) (NeuAca(2—>3)Galp( 1 —>3) [Fuca(l— 4)]GlcNAc) and sialyl Lewis X (sLex)50 (NeuAca(2—>3)Galp( 1 —>4)... 

Carbohydrate-mediated cell adhesion is an important event which can be initiated by tissue injury or infection and is involved in metastasis. One such adhesion process is the interaction between the glycoprotein E-selectin and oligosaccharides on the surface of neutrophils (white blood cells). The ligand that E-selectin recognizes is the tetrasaccharide sialyl Lewis X (SLe ). Since SLe competes with white blood cells for binding to E-selectin, thus inhibiting the adhesion process, it may useful as an anti-inflammatoiy and anticancer agent. 

Mimetics of sialyl Lewis X, the terminal tetrasaccharide of glycoproteins and glycolipids that are known to interact with selectins in the inflammatory process, have been efficiently synthesized through the use of the enzymatic aldol condensation (Scheme 5.26).29 This straightforward approach involved the condensation of mannosyl aldehyde derivatives with DHAP in the presence of DHAP-dependent aldolases. The aldehyde acceptors are generated from mannose by protection of the anomeric center as allyl ether, followed by... 

Blixt O, Norberg T. Solid-phase enzymatic synthesis of a sialyl lewis X tetrasaccharide on a sepharose matrix. J. Org. Chem. 1998 63 2705-2710. 

Nicolaou s synthesis [7] of the Sialyl-Lewis tetrasaccharide is discussed in detail as an example of the stepwise route (Scheme 5.4). 

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