Glycosylation sialylation

O-glycosylated sialylated amino acids and peptides in urine Angiotensin II (26.8 nM)... 

Post-transla tional Degree of glycosylation, sialylation. 

Sphingoglycolipid Glycosphingolipid Ceramide Sphingosine Dihydrosphingosine Phytoshingosine Sialic acid Glycosylation Sialylation DSLe Cerebroside Plakoside... 

Froesch, M. Bindila, L. Zamfir, A. Peter-Katahnic, J. Sialylation analysis of O-glycosylated sialylated peptides from mine of patients suffering from Schindler s disease by Fourier transform ion cyclotron resonance mass spectrometry and sustained off-resonance irradiation collision-indnced dissociation. Rapid Communications in Mass Spectrometry 2003,17, 2822-2832. 

The recent impressive work from Hamilton and Gerngross [66] about controlled humanization of iV-glycosylation opened up very attractive perspectives for yeasts for large-scale production of eukaryotic fully humanized sialylated glycoproteins. That makes them serious... 

BF3-OEt2 Unnatural P-sialoside derivatives are produced preferentially by using O-acetylated glycosyl fluoride donor and BF3-OEt2 as the promoter. When P-sialyl fluoride derivative 28 was reacted with acceptor 22 in the presence of BF3-OEt2 in dichloromethane, the P-sialoside 28 was obtained in a mixture of anomers (a/p 17/83) (Scheme 2.11) [44],... 

Takahashi and coworkers described an effective sialylation method utilizing the N-Fmoc, N-Troc and N-trichloroacetyl-P-thiophenyl sialosides (Scheme 4.6d) [167]. It was found that the N-Troc derivative of N-acetylneuraminic acid performed better than the corresponding N-Fmoc derivative. An N-Troc P-thiosialoside was applied for the synthesis of glycosyl amino acids by one-pot glycosylation [167]. Importantly, it was found that the N-Troc protecting group could be converted into an acetamido moiety without causing racemization of the peptide. 

Wong and coworkers showed that 5-azido sialyl donors protected with O-acetyl ester are useful for a-selective glycosylations of primary hydroxyls (Scheme 4.6e) [169]. It was proposed that the linear and electron-withdrawing nature of the C-5 azido moiety stabilizes the reactive axial acetonitrile adduct to allow the incoming nucleophile to approach the a-face in an SN2-like fashion. In addition, a chemose-lective glycosylation method has been developed for the synthesis of NeuAca-(2 —> 9) NeuAc as thioglycoside donor for use in the subsequent glycosylations [169]. 

Scheme 4.74 Sialyl xanthate in regioselective and stereoselective glycosylations [398].

Figure 14.2 Representative oligosaccharide structures found on mammalian glycoproteins and glycolipids. The complex oligosaccharides may be bi-, tri-, or tetra-antennary the branches may be more or less elongated with 1—>4 linked lactosamine units, and they may or may not be sialylated. The SLex, Lea, and Leb structures represent the different blood group determinants often present on lipids, and the elongated core 2 structure is a mucin-type glycosylation. Proteoglycans have a common core to which a variety of linear acidic polysaccharides are attached.

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