Monosaccharide composition proteins

Characteristics of fraction I. The carbohydrate content of Fraction I was 84.4 %, in which the main component is D-galacturonic acid (71 %). Consequently, the polysaccharide is of a pectic type. The neutral sugars accounted for 13.4 % and according to their qualitative composition (Table 2) they correspond to the composition of pectin, isolated from sunflower heads (18). It is worth noting the high content of L-arabinose and D-galactose, compared with the other monosaccharides. The protein content was 7.8 %. 

This intrinsic property of carbohydrates considerably limits the success of any de novo assignment of monosaccharide composition, although such a technique is feasible for amino acids in proteins (contingent on accurate mass values of the peptide precursor ion and a small number of accurate fragment ion mass values) [19],... 

Carbohydrate content (%, w/w) and monosaccharide composition (nmol sugar/mg protein) of Hcs from various... 

If oligosaccharides are not cleaved from the protein by acid hydrolysis but by y0-elimination for determining monosaccharide composition, as is done for... 

Monosaccharide composition analysis is often done to detect the presence of uncommon or atypical monosaccharides that may be present on the protein backbone, often in O- or C-linked forms. Typically, monosaccharides are released in strong acid at high temperature. However, it must be noted that hexose linkages are usually more stable to heat and strong acid than those of fucose or sialic acids. For instance, sialic acids are known to decompose after prolonged exposure to heat and acid. Optimizing the release of monosaccharides require careful sample... 

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. 

Rha, Ara and Gal are the neutral sugar components from all the fractions. Xyl is not present in Fla and is significantly present in the hemicellulose fractions, indicating that this monosaccharide is component of hemicellulosic polymers. Chemical composition of the water fractions were determined (Table V). High protein contents and the presence of O-acetyl-groups were observed in four aqueous fractions. Neutral sugar and uronic acid composition points to inclusion of these polymers in the class of pectic polysaccharides. 

Naturally occurring polysaccharides are made up of a variety of monosaccharides connected by glyco-sidic bonds. Often, these polysaccharides are linked to proteins and lipids. The function of such polysaccharides is often critically dependent on the composition and sequence of their monomeric units. Determination of the structure of polysaccharides is a multistep process. In the early stages, it is crucial to ascertain both the relative amount and the chemical identity of the monomers. After a polysaccharide has been broken down to its monomeric units by hydrolytic or enzymatic digestion, a variety of analytical techniques can be employed to identify and quantify each monomer. Three of these techniques will be demonstrated in this laboratory exercise. 

The cells grown in high density culture medium at SO C were analyzed for protein, carbohydrate, lipid and vitamins. Amino acid, monosaccharide and fatty acid compositions were also determined. 

Glycosaminoglycans are solubilized from stromal or other tissues by extracting the source tissue with dilute acid or alkali. Hyaluronan is electrostatically bound to specific proteins called hyaladherins, which possess a structural domain of -100 amino acids termed a link module. Other glycosaminoglycans are O-linked to serine and threonine residues of polypeptides and these bonds hydrolyze before the rest of the polysaccharide. The protein moiety precipitates when trichloroacetic acid or ammonium sulfate is added to the cooled mixture. The composition of the GAGs (including hyaluronan) was identified by chromatographic separation of the purified polysaccharides, followed by their hydrolysis in boiling 1.0 M HC1 for 2 1 h and identification of the individual monosaccharide components. 

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