Oligosaccharides methylation

The kinetics of alkaline degradation of methyl B-D-xylopyranoside and several oligosaccharide methyl glycosides based on wood xylans have been examined as models for the processes occurring in the... 

The methods used to elucidate the linkage positions in an oligosaccharide (methylation, oxidative cleavage of glycols) were outlined under monosaccharides. 

Celik, S. E., M. Ozyiirek, K. Gii lii, and R. Apak. 2007. CUPRAC total antioxidant capacity assay of lipophilic antioxidants in combination with hydrophilic antioxidants using the macrocyclic oligosaccharide methyl P-cyclodextrin as the solubility enhancer. React. Funct. Polym. 67 1548-1560. 

As impressive as the oligosaccharide domain is, calicheamici-none, the aglycon sector 7 (see Scheme 3) is the most striking substructure of calicheamicin y. The rigid bicyclic framework of 7 accommodates an unusual allylic methyl trisulfide and a novel pattern of unsaturation that had not been encountered in natural products before. 

Deoxy-sugars. Part XVIII. Synthesis of an Oligosaccharide by the Thermal Condensation of ap-Methyl-2-deoxy-D-ga actofuranoside, W. G. Overend, F. Shafizadeh, and M. Stacey, /. Chem. Soc., (1951)994-997. 

Xylans as true homopolymers occur in seaweeds of the Palmariales and Nemaliales, however, their backbone consists of Xylp residues linked by -(1 3) (Type X3, Fig. la) or mixed -(1 3, 1 -> 4)-glycosidic linkages (Type Xmy Fig. lb). They are assumed mainly to have a structural function in the cell-wall architecture, but a reserve function cannot be ruled out [4]. From the microfibrils of green algae (Siphonales) such as Caulerpa and Bryop-sis sp., X3 was isolated and the structure confirmed by methylation analysis, C-NMR spectroscopy [7], as well as by mass spectrometry of enzymically released linear oligosaccharides up to a degree of polymerization (DP) of... 

Coenzymes serve as recyclable shuttles—or group transfer reagents—that transport many substrates from their point of generation to their point of utilization. Association with the coenzyme also stabilizes substrates such as hydrogen atoms or hydride ions that are unstable in the aqueous environment of the cell. Other chemical moieties transported by coenzymes include methyl groups (folates), acyl groups (coenzyme A), and oligosaccharides (dolichol). 

A detailed study of the 0-linked oligosaccharides present on the surface of normal granulocytes, chronic myelogenous leukemia cells, and acute myelogenous leukemia cells has been completed. Structures were elucidated by f.a.b.-m.s. after permethylation, and methylation analysis before and after specific exo-glycosidase treatments. Some of the components were shown by f.a.b.-m.s. to be poly(N-acetyllactosaminyl) oligosaccharides, for example, 29. 

In a study completed during the early development of f.a.b.-m.s., both f.d. and f.a.b. were used to characterize 101 fractions containing neutral oligosaccharides isolated from human milk. Samples were examined as their peracetylated alditols. In subsequent work, the structures of two minor acidic oligosaccharides from human milk were investigated. The per-methylated derivatives were analyzed by f.a.b.-m.s., and their compositions and sequences were defined by the f.a.b. data. Methylation analysis and partial formolysis were the other principal methods used. 

Cello- and malto-oligosaccharides up to nonasaccharides in the presence of various metal salts have been analyzed by f.a.b.-m.s. The structures of two methyl alduronates obtained by flash hydrolysis of wood chips was deduced by using f.a.b.-m.s., n.m.r. spectroscopy, and sugar analysis. ... 

Oligosaccharides were isolated from PMII by weak acid hydrolysis and separation by SEC and HPAEC-PAD. The isolated oligosaccharides were desalted, reduced and methylated. GC-MS analysis of the partially methylated alditol acetates has been used to reveal the structure of the oligosaccharides. 

Oligosaccharides were methylated using NaOH in DMSO for sugar alkoxide formation(2). 

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