Monosaccharides Monosaccharide sequences

A number of glycosidic hydrolases have been produced in sufficiently pure form to allow the development of a method of determination of monosaccharide sequences based on these enzymes (Table 6.4). These enzymes will remove specific monosaccharide units linked by specific linkages from the nonreducing end of a polysaccharide. For example, P-galactosidase will remove D-galactosyl residues linking p-glycosidically to polysaccharide. The use of sequential enzymatic hydrolysis is a well-established technique, particularly for the analysis of the carbohydrate residues of macromolecules. 

Monosaccharide sequence, linear/branched, glycosidic linkages, nonreduced —> reduced... 

At 6 A resolution, the macromolecule usually appears as a blob of electron density and the chain backbone is generally unrecognizable. At 3.0 A resolution, it is possible to trace the path of the macromolecular chain backbone. The double helices of nucleic acids are traced readily. At 2.0 A resolution, almost all protein side chains, nucleic acid nucleotides and polysaccharide glycoses are visible. A model of the protein, nucleic acid or glycan can be constructed if the amino acid, nucleotide or monosaccharide sequence is known. At higher resolution, individual atoms begin to be seen. It is possible to identify amino acid side chains, nucleotides and glycose units directly from the electron density map. 

Hyaluronic acid is a naturally occurring polysaccharide comprising monosaccharide sequences with carboxylic or acetamido side groups. Early production of hyaluronic acid, a biodegradable polymer similar to chitosan, was achieved through extraction of natural tissues, and the evolution of hyaluronic acid technology was made possible after its successful production in sufficient quantities as a fermentation product. The key evolution of... 

Studies on pinocytosis by human fibroblasts of j8-D-2-acetamido-2-deoxy-hexosidase have led to the conclusion that a neuraminidase deficiency in I-cell disease may not be directly responsible for excessive extracellular /S-d-2-acetamido-2-deoxyhexosidase. The proposed neuraminidase deficiency in I-cell disease has been discussed in the light of its significance in influencing the final monosaccharide sequence in the carbohydrate structure of the recognition site of the fibroblasts-derived j8-D-2-acetamido-2-deoxyhexosidase. ... 

Evidence is accumulating that relatively minor changes in the primary monosaccharide sequence produces changes in... 

It was outhned in the introductory section (cf. 4.4.1) that the periodically arranged monosaccharide sequence in a polysaccharide can be interrupted by nonperiodic segments. Such... 

KDO has chemical properties similar to those of neuraminic acid as it has a carboxylate group, a 3-deoxy group, and a similar biosynthesis (see Chapter 10). The monosaccharide composition, sequence, and linkages, along with the position of attachment of phosphate and ethanolamine pyrophosphate substituted onto the heptose residues of the core polysaccharide have been determined [53-58] and are shown in Fig. 9.16C. The fatty acids in the lipopolysaccharide participate in the formation of a lipid bilayer for the outer membrane. The carbohydrate is hydrophilic and is located on the outer faces of the lipid bilayer membrane. The O-antigen polysaccharides and other capsular polysaccharides are attached to position-4 of the next to last monosaccharide residue, a-D-glucopyranose of the core polysaccharide. 

In conclusion, it may be reasonably assumed that if a protein contains covalentlS linked carbohydrate, then an affinity chromatographic ccdumn based on a lectin or panB of lectins, can be selected for detailed evaluation of the monosaccharide composition sequence and branching patterns. Such lectin affinity chromatography is a rapid, hi resolution non-destructive analytical procedure that can be applied to trace quantiti of material. New lectins are constantly being discovered, so we can safely anticipate the availability of progressively more refined lectin analytical reagents. 

A pentahexosyl ceramide from dog intestine with the monosaccharide sequence GalNAc-GalNAc-Gal-Gal-Glc-Cer was described (W. R. Vance et al., 1966 McKibbin, 1968, 1969). 

Spiro, R.G. Studies on the Monosaccharide Sequence of the Serum Glycoptotein Fetuin. / Biol. Chem. 1962, 237, 646-652. 

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