Disaccharides linkages

The primary formation of o-gluconic acid and o-glucosone simultaneously with o-glucose and o-fructose may be accounted for by two types of oxidative scission of the disaccharide linkage, at a and b. The former leads to D-fructose and... 

The G galactose of formulas 16.1 to 16.3 may be linked in four different ways to the carrier chain of the glycoconjugate, in the so-called types 1 to 4, shown in Table 16.1. We would like to point out that the galactose on the left in Table 16.1 is the G galactose of the ABH antigens. The distribution of these types of disaccharide linkages depends on the family of the glyconjugate carrier. 

It often occurs that collisional spectra may eliminate stereochemical ambiguities. As an example, the disaccharide linkage in a free molecule may be determined by analyzing B/E/CAD spectra of molecular ions produced by field desorption [235]. The disaccharides trehalose (1 1), sophorose (1 - 2), nigerose (1 3), cellobiose (1 -+ 4)... 

In addition to distinguishing the disaccharide linkage bond in various stereomeric species, measurements of collisional-induced decompositions (as MIKE/CAD spectra) also enable one to differentiate the diastereomeric disaccharides themselves, providing that protonated molecular ions are not used [236]. 

In the study of the structure of the cell-wall polysaccharides of a poorly characterized Proteus microorganism, a new type of disaccharide linkage, structure (24), in bacterial polysaccharides was discovered (152). Presumably, this is the first example of an open-chain gly-cosidic linkage however, it is not clear whether this new linkage has important biological meaning. 

One reason for studying the conformation of the disaccharide maltose is that it contains the same interresidue linkage as found in amylose and amylopectin, the polymers of starch. Therefore, conformations of the maltosyl linkages found in maltotriose or panose would certainly be of interest in the comparison with a calculated energy surface. It would be obvious to include a-maltose, -maltose, and methyl- -maltoside, molecules that differ only at the anomeric center, which is as distant as possible from the disaccharide linkage and therefore unlikely to affect the linkage conformation very much. 

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