Polysaccharides

The objective of this article is to illustrate and visualize the structures and concepts of common polysaccharides that are difficult to visualize and illustrate by viewing two dimensional structures in textbooks. Structures with a 3D perspective are used to illustrate features of a molecule which can not be easily visualized using 2D structures.

Unbranched chain, α(1→4) glycosidic bonds Amylose is an example of a polysccharide which contains thousands of glucoses connected by α(1→4) glycosidic bonds. The initial view () shows an eleven unit segment of amylose with yellow halos marking some of the oxygens which form the 1→4 glycosidic bonds. Rotate to view the glucopyranosyl units on edge to see that the bonds are α linkages. (Remember: With the glucose providing C-1 on the left, the glucose providing C-4 on the right and C-6 of the glucoses projecting to the back of the screen both bonds of the oxygen of the α linkage project down.) From this perspective you are looking down the axis of a helix that is formed as a result of the angle that is form between the glucopyranosyl residues when they are connected by the α(1→4) bonds. This characteristic of the α(1→4) bond was seen when studying maltose. ends of the polymer yellow and green. with 20 glucose units; Branched chain, α(1→4) glycosidic bonds is also a large glucose polymer that has α(1→4) glycosidic bonds connecting the glucose units, but it also contains α(1→ 6) glycosidic bonds. In this scene the main branch is colored yellow, the side branch is green and the oxygen atoms of the α(1→4) bonds are red. Rotate to view the glucopyranosyl units on edge and verify that the bonds are α linkages. , branching point, colored yellow with the oxygen atom connecting C-6 of unit four to the C-1 of the side chain colored green. The is colored CPK, C-1 of this unit is able to open to the aldehyde and function as a reducing agent, but all the other termini of an amylopectin molecule are non-reducing because the C-1 of these terminal units are involved in glycosidic bond and can not form the aldehyde. In this scene the non-reducing termini are colore green. The native amylopectin having many more branching points would be more open than this structure, in fact it would have very little curvature. Rotating & zooming amylopectin gives a focused view of the α(1→ 6) bond.

spinqualitylabelsall models Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

spinqualitylabelsall models Insert caption here Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Other Carbohydrate PagesOther Carbohydrate Pages

• Hexoses
• Disaccharides