Cleavage of glycosides

Because of its importance to carbohydrate technology, biochemistry, and physical organic chemistry, the hydrolytic cleavage of glycosides has been extensively studied with respect to both acid and enzymic catalysis. Reviews on the acid-catalyzed hydrolysis have been presented by BeMiller, Capon, ... 

Alkali-catalyzed cleavage of glycosidic bonds of glycosaminoglycur-onates occurs by way of -elimination.223 By proper choice of the experimental conditions, it seems possible to achieve a controlled degradation of heparin by -elimination, producing fragments apparently preserving... 

For endopectate lyases, the rate of cleavage of glycosidic bonds and the affinity of the enzyme for the substrate depend on the chain length,240,241 as with endo-D-galacturonanase. The frequency of splitting of bonds 2 and 3 in tetra(D-galactosiduronic acid) is different. Endopectate lyase of Bacillus polymyxa splits240 bond 3 1.4 times faster than bond 2. 

Substituent effects on the endocyclic cleavage of glycosides by trimethylaluminium have been explained in terms of a cyclic C-H O hydrogen-bonded intermediate. ... 

HYDROLYSIS AND OTHER CLEAVAGES OF GLYCOSIDIC LINKAGES IN POLYSACCHARIDES... 

This article is a discussion of cleavage of glycosidic linkages useful for the analysis of oligo- and poly-saccharides. 

It is useful to arrange a discussion of the literature concerning acid hydrolysis by type of substrate, and then to subdivide by type of acid used for a substrate, even though this may mean some overlap. It should also be kept in mind that many of the references for cleavage of glycosidic... 

Formolysis and acetolysis are not common methods for cleavage of glycosidic linkages. They do have some unique applications, however. For instance, methylated polysaccharides are not generally soluble in hot water, and consequently, hydrolysis is best preceded by formolysis under these circumstances. For example, 5 mg of methylated polysaccharide is dissolved in 3 mL of 90% formic acid, and the solution is kept for 2 h at 100°. The formic acid is removed by evaporation at 40°. The residue is dissolved in 1 mL of 250 mM sulfuric acid and the solution is heated for 12 h at 100°, cooled, the acid neutralized with barium carbonate, the... 

IWo chapters treat widely divergent aspects of the aqueous degradation of carbohydrates. Christopher J. Biermann (Corvallis) discusses aqueous acidic hydrolysis and other cleavages of glycosidic linkages in oligo- and polysaccharides, with specific emphasis on their relation to procedures for determination of chemical structure. In the final chapter, Olof Theander (Uppsala) and David A. Nelson (Richland) provide an informative treatment of the... 

S. G. Withers, Enzymatic cleavage of glycosides How does it happen, Pure Appl. Chem., 61 (1995)... 

Fig. 3 Selective cleavage of glycosidic residues from ginsenosides by ginsenosidase...

Since mechanisms for the cleavage of glycosidic bonds by a- and )S-glycosidases are different, a fluorosugar has a different behavior when it is the substrate of the two... 

CgFIgOs, Mr 152.15, pi.3kPa 155 °C, df 1.056, is found in many essential oils and foods, but is often not essential for their odor or aroma. However, it does determine the odor of essential oils and extracts from Vanilla planifolia and V. tahitensis pods, in which it is formed during ripening by enzymatic cleavage of glycosides. 

Jpe selective, nonhydrolytic cleavage of glycosidic linkages [Eq. (8) 13]. This process is HtSeful in detennining structures of complex carbohydrates [14]. 

On the other hand, Bennet and Sinnott provided evidence that an antiperiplanar lone electron pair is not needed in acid-catalyzed cleavage of glycosides via a carbocationic intermediate.53 54 Theories of stereoelectronic control must be applied to enzymes with caution ... 

A. V. Perepelov, S. N. Senchenkova, A. S. Shashkov, N. A. Komandrova, S. V. Tomshich, L. S. Shevchenko, Y. A. Knirel, and N. K. Kochetkov, First application of triflic acid for selective cleavage of glycosidic linkages in structural studies of a bacterial polysaccharide from Pseu-doalteromonas sp. KMM 634, J. Chem. Soc. Perkin Trans. 1 (2000) 363-366. 

Due to Random Cleavage of Glycosidic Bonds by Keteniminium Ions. .. 180... 

Scheme 21 Cleavage of glycosidic bonds in cellulose by N.N-dimethylketeniminium ions (46)...

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