Carbohydrates glucosamine

Another structural variation is the replacement of a hydroxyl group m a carbohydrate by an ammo group to give an ammo sugar The most abundant ammo sugar is one of the oldest and most abundant organic compounds on earth N Acetyl d glucosamine is the... 

Recently, Li et al. [30], Yu et al. [31] reinvestigated the mechanism of graft copolymerization of vinyl monomers onto carbohydrates such as starch and cellulose initiated by the Ce(IV) ion with some new results as mentioned in Section II. Furthermore, they investigated the mechanism of model graft copolymerization of vinyl monomers onto chitosan [51]. They chose the compounds containing adjacent hydroxyl-amine structures, such as D-glucosamine, /mn5-2-amino-cyclohexanol, 2-... 

Amino-2-deoxy-a-D-glucose (a-D-Glucosamine) from Crustacean Shell, M. Stacey and J. M. Webber, Methods Carbohydr. Chem., 1 (1962) 228-230. 

Figure 13-10. Glucosamine (2-amino-D-glucopyra-nose) a form). Galactosamine is 2-amino-D-galactopy-ranose. Both glucosamine and galactosamine occur as N-acetyl derivatives in more complex carbohydrates, eg, glycoproteins.

The anion of nitromethane adds easily to the carbonyl functions of sugars. This is a useful strategy for extension of the carbon chain.100 2-Acetamido-2-deoxy-P-D-glucose (A-acetyl-D-glucosamine) is the carbohydrate unit of glycoproteins that occurs most often. The nitromethy-lation method provides a straightforward route to a series of C-glycosyl compounds with the acetamido functionality (Eq. 3.62).101... 

In all cases where the chemical properties of these preparations have been studied the active material appears to be predominantly carbohydrate in nature, containing in the case of the A factor 50-70% of reducing sugar, 5.7% nitrogen and giving by colorimetric estimations 25-30% of glucosamine on hydrolysis. 

It was found possible to saponify ovomucoid with sodium hydroxide and to methylate simultaneously with methyl Bulfate, the carbohydrate residue thereby forming an N-acetyl methyl derivative.14 Hydrolysis of this material yielded N-acetyl-3,4,6-trimethyl-D-glucosamine (7 moles) (LIVJ, D-mannopyranose (2 moles) (LV), 3,4,6-trimethyl-D-mannopy-ranose (1 mole) (LVI), and tetramethyl-D-galactopyranose (1 mole) (LVII). 

From the identification of these products it was possible to give a means of portraying the type of structure (LVIII) present in the carbohydrate molecule. In this, by glycosidic attachment, seven N-acetyl-D-glucosamine unitB and one D-galactose unit radiate from a central core of three D-mannose units. It is not yet clear by what linkages the d-mannose units are mutually attached, or to which D-mannose the d-galactose residue is linked. 

The thyreotropic hormone166 from pituitary extracts appeared to be an entity separate from the luteinizing hormone and contained nitrogen, 13% carbohydrate, 3.5% and D-glucosamine, 2.5%. 

K. Krenek, M. Kuldova, K. Hulfkova, I. Stibor, P. Lhotak, M. Dudic, J. Budka, H. Pelantova, K. Bezouska, A. Fiserova, and V. Kren, /V-Acetyl-D-glucosamine substituted calix[4]arenes as stimulators of NK cell-mediated antitumor immune response, Carbohydr. Res., 342 (2007) 1781-1792. 

Carbohydrate molecules containing amine groups, such as D-glucosamine, easily may be conjugated to other macromolecules using a number of amine reactive chemical reactions and crosslinkers (Chapter 2, Section 1 and Chapter 3). Some polysaccharides containing acetylated... 

Most of the LPS biological activity (pyrogenicity) is associated with its lipid A moiety. This usually consists of six or more fatty acids attached directly to sugars such as glucosamine. Again, as is the case in relation to the carbohydrate component, lipid A moieties of LPS isolated from different bacteria can vary somewhat. The structure of E coli s lipid A has been studied in the greatest detail its exact structure has been elucidated and it can be chemically synthesized. 

Tungsten aryloxo complexes have been shown to catalyze the intramolecular metathesis reactions of di- and tri-substituted co-unsaturated glucose and glucosamine derivatives to yield bicyclic carbohydrate-based compounds containing 12- and 14-membered rings [108,214,215]. An example is shown in Eq. 37. The tolerance for amides and esters is noteworthy, as are the yields and the size of the rings that are formed. 

Fig. 8. First synthesis of carbohydrate-substituted polymers by ROMP using a defined orga-nometallic initiator. Grubbs synthesis of glucosamine-substituted polymers...

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