The Sugar Chains

Endo, T., Wright, A., Morrison, S.L., and Kobata, A. (1995) Glycosylation of the variable region of immunoglobulin G-site specific maturation of the sugar chains. Mol Immunol. 32(13), 931-940. 

A comparative analytical study, by means of paper chromatography, has confirmed the conclusion that, in the condensation of aldoses with ethyl acetoacetate, the yield of the furan derivatives increases as the length of the sugar chain is decreased.17... 

Fig. 36 Example of synthesis of an imino sugars by insertion of the nitrogen on the sugar chain and subsequent cyclization at the anomeric centre.

A consideration of the individual carbon atoms of the sugar chain thus leads to the conclusion that this trimethylglucose is the 2,3,6-isomer and ample confirmation of this conclusion has been forthcoming. To mention only two cases (a) oxidative degradation yields L-threo-di-methoxysuccinic acid,143 and (b) the sugar does not condense with acetone.130... 

The cyanohydrin synthesis of higher sugars, which involves intermediate aldonolactones, allows the introduction of a 14C label in the sugar chain. Thus, for example, L-[5-l4C]arabinose was synthesized (12) from D-xylose, which was first converted, by addition of K14CN and hydrolysis, into D-[ 1-... 

Kobata A (1987) Malignant transformational changes of the sugar chain and their clinical applications. In Greene MI, Hamaoca T (Eds) Development and recognition of the transformed cells. Plenum New York, p 385... 

The complex structure isolated from Scleranthus uncinatus, 5,7-dihydroxy-3 -meth-oxy-4 -acetoxyflavone-8-C-p-D-xylopyranoside-2 -0-glucoside, was determined by using ID NMR ( H, C, DEPT) and 2D NMR (H-COSY, TOCSY, HMQC, HMBC, NOESY) data sequence and linkage of the sugar chain and acylation site were confirmed by observation of inter-residue NOEs in the NOESY spectrum. 

During the past decade, there has been intense activity in the study of the synthesis and reactions of carbohydrate derivatives containing a carbon-carbon double bond in the sugar chain. Ferrier107 has summarized the status of knowledge in this area, up to 1969, in earlier Volumes of this Series. A wide variety of rare and modified sugars can be synthesized by way of addition reactions to unsaturated sugars ... 

SAMPLE SOLUTION (a) The a-hydroxy aldehyde unit at the end of the sugar chain is cleaved, as well as all the vicinal diol functions. Four moles of periodic acid are required per mole of D-arabinose. Four moles of formic acid and one mole of formaldehyde are produced. 

The sugar chain of ARS2 was oxidized, partially cleaved with 30 mM NaIC>4 at 4°C in the dark, and reduced with NaBH4 at room temperature overnight. For controlled Smith degradation, the polyol derivatives of ARS2 were hydrolyzed with 100 mM H2SO4 at room temperature for 16 hr. 

Presence of a methylene group in the sugar chain (e.g., the 2-deoxy group of compound 31) greatly increases the reactivity this effect will be discussed subsequently (see p. 195). 

As a result of these considerations, a rejuvenescence of interest in sulfonic esters of acyclic-sugar derivatives, e.g., of sugar mercaptals, is to be expected, since they afford a route to the synthesis not only of compounds having one or more methylene groups at desired positions in the sugar chain (of which 2-deoxy-D- ribose, or 2-deoxy-D-eryother groupings, e.g., double bonds, at selected positions in the chain. 

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