Carbohydrate residues oxidation

The methods of oxidant consumption are used exclusively in the analysis of residual lignin in unbleached pulps. These procedures are all based on the common principle that lignin consumes the appHed oxidants at a much faster rate than the carbohydrates, and oxidant consumption under carefully specified conditions can be regarded as a measure of lignin concentration in the pulp. 

Oxidation of IgG Carbohydrate Residues with Sodium Periodate... 

Biotin-hydrazide has been used to biotinylate antibodies at their oxidized carbohydrate residues (O Shanessy et al., 1984, 1987 O Shanessy and Quarles, 1985 Hoffman and O Shannessy, 1988), to modify the low-density lipoprotein (LDL) receptor (Wade et al., 1985), to biotinylate nerve growth factor (NGF) (Rosenberg et al., 1986), and to modify cytosine groups in oligonucleotides to produce probes suitable for hybridization assays (Reisfeld et al., 1987) (Chapter 27, Section 2.3). 

The following protocol describes the use of biotin-hydrazide to label glycosylated proteins at their carbohydrate residues. Control of the periodate oxidation level can result in specific labeling of sialic acid groups or general sugar residues (Chapter 1, Section 4.4). 

Structural investigations into the degree of branching and into the position and nature of glycosidic bonds and of non-carbohydrate residues in polysaccharides may include periodate oxidation and other procedures such as exhaustive methylation. X-ray diffraction and spectroscopic techniques such as nuclear magnetic resonance and optical rotatory dispersion also give valuable information especially relating to the three-dimensional structures of these polymers. 

A role for the carbohydrate moieties in the catalytic process of an enzyme was suggested many years ago.24 However, studies with several different enzymes19,149,150 have shown that enzymic activity is affected only slightly if the carbohydrate residues are oxidized with periodate. Furthermore, removal of carbohydrate residues with gly-cosidases,1,15 followed by measurements of activity, has shown that the resulting, modified enzymes had specific activities that were essentially unchanged. With ribonuclease B, it has also been con-... 

Secondly, selective chemical modification may be performed because the carbohydrate residues have a distinct low reactivity. This can be done by periodate oxidation which cleaves C-C bonds bearing adjacent hydroxyl groups and converts them to aldehydes [25,26]. The generated dialdehyde can react with a variety of nucleophiles - usually primary amino groups on the surface of carrier materials. The resulting Schiff bases can be further stabilized by sodium boro-hydride, sodium cyanoborohydride or pyridine-borane reduction [27]. 

These 5-hydroxy-L-lysine residues are known to be formed by the oxidation of L-lysine residues present in completed polypeptides. (b) A search for aminoacyl negative results. (c) Although puromycin inhibited polypeptide synthesis, it did not inhibit the attachment of carbohydrate residues to the preformed polypeptide molecules. (d) Incorporation studies with cell-free systems also supported this conclusion, as discussed later. 

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