Monosaccharides structure, enzymic analysis

Another Arabidopsis mutant, murl, which lacks the ability to synthesize 1-fucose, possesses a defective gene encoding GDP-d-Man-4,6-dehydratase, a key enzyme in 1-fucose biosynthesis. Further analysis revealed that 1-Fuc is replaced by 1-Gal, a structurally similar monosaccharide, in the cell walls of this mutant with no adverse effects on plant physiology or metabolism (Rayon et al, 1999). Transgenic plants containing this mutation can also be used for foreign protein production. 

Chemical structure elucidation of the carbohydrate moiety of a glycoprotein is a difficult problem because there is often chain branching and because the individual carbohydrate chains are not always identical. Specific exoglycosidases which release monosaccharide units only from the terminal nonreducing end of the carbohydrate chain are most useful in structural analysis. Among the enzymes available for sequence analysis... 

Also, they are used for the structural analysis of carbohydrates (117). The information obtained is not limited to that obtained by analysis of the hydrolysis fragments because the specificity of enzyme action, a specificity based on type of monosaccharide and type of linkage, leads to significant data being obtained, by a process of elimination, from enzyme resistant structures and partially hydrolyzed structures. The enzymes which hydrolyse polysaccharides are divided into two groups, endo- and exo-polysaccharide hydrolases. Endo- polysaccharide hydrolases are specific for linkage and... 

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