Botany online 1996-2004. No further update, only historical document of botanical science!

Disaccharides and Glycosidic Bonds


Sucrose - the disaccharide important for the nutrition is - as other sugars too - not a rigid, but a flexible structure.

Formation of a Disaccharide: The figure llustrates the combination of alpha D-glucose and a D-fructose unit to form the disaccharide sucrose
Highlights some of the important structural features of polysaccharides in general and of sucrose in particular.
© Thomas A. NEWTON

Monosaccharide subunits condense (react under the splitting off of water) to form disaccharides with glycosidic bonds. Here, it is distinguished between the alpha- and the beta- glycosidic bond. Some important examples are:

sucrose

consists of a alpha-glycosidically linked glucosyl-residue and a fructosyl-residue. Then the

where the galactosyl-residue and the glucosyl-residue are linked alpha-glycosidically. The

with an alpha-glycosidic bond between two glucosyl-residues and the

where two glucosyl-residues are linked in a beta-glycosidic way.

In all these cases, one residue is linked with its C1-atom to the C4-atom of the other sugar residue (a 1 > 4 glycosidic bond).

We will later on also meet 1 > 2, 1 > 3 and 1 > 6 glycosidic bonds.

© Peter v. Sengbusch - Impressum