Glycosylated conjugates

Monomeric carbohydrates in their cyclic form (furanoses and pyranoses) are hemiacetals, which, to become acetals, form 0-glycosyl conjugates. The C-atom C(l) that bears two O-atoms is the reactive, electrophilic center targeted by glycosidases. Nonenzymatic hydrolysis is also possible, although, as a rule, under physiological conditions of pH and temperature, the reaction is of limited significance. 

Structure 1 of Glycans O-Glycosylically Conjugated Through the Linkage a-GalNAc-(l— 3)-Ser or Thr... 

Flavonols that accumulate in plant tissues are almost always in the form of glycosylated conjugates. The main flavonols in onions are quercetin- 4 -O-glucoside and quercetin-3,4 -0-,diglucoside with smaller amounts of isorham-netin-4 -0-glucoside (Fig. 1.3) [Mullen et al., 2004]. 

The C-glycosyl conjugate 139, containing biotin, and several related compounds were prepared and their inhibitory activity towards the receptor-mediated adhesion of E. coli to yeast cells was tested. " ... 

FIGURE 6.8 Glycosylated conjugates of radioiodinated 7,8-dicarba-mdn-undecaborate (-1) (96-99). 

Various synthetic routes to novel nucleoside diphosphate derivatives have been described. Tonn and Meier describe a solid-phase protocol for the synthesis of cjc/oSal-protected nucleoside monophosphates, which can then be used for the synthesis of diphosphates and triphosphates, and conjugates of both, by treatment with the appropriate phosphate or pyrophosphate derivative, including methylene pyrophosphate derivatives. " A synthesis of lamivudine (3TC) diphosphate has been reported which involves oxidation of lamivudine /f-phosphonate, conversion of the phosphate to its imidazolate followed by reaction with phosphate. A few syntheses of glycosyl conjugates of nucleoside diphosphates, e.g. (17), have been reported for their study with glycosyltransferases, which play a key role in a variety of cellular processes. ... 

One of the main classes of nucleoside diphosphate derivatives are the p-glycosyl conjugates. A one-step synthesis of O-acetyl-ADP-ribose and its derivatives has been deseribed starting from NAD. Uridine diphosphate V-acetylglucosamine (20) (UDP-GlcNAc) is ubiquitously found in eukaryotes involved in post-translational modification of proteins. Using... 

A fluorescent glycosyl azide 127 was clicked with alkyne 128 and afforded fluorescent triazolyl glycoconjugate 129 (Scheme 6.34). The developed fluorescent-labeled biomolecules 129 are likely to be an important tool for investigating various biological events. The fluorescent glycosyl conjugates were used to trace the translocation route of glycosyl pesticides within plants [75]. 

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