Cellobiose, 1—»4-/3-link structure

Cellulose consists of several thousand o-glucose units linked by l- 4-/3-glyco-side bonds like those in cellobiose. Different cellulose molecules then interact to form a large aggregate structure held together by hydrogen bonds. 

Cellobiose and maltose are both disaccharides made up of two glucose units. The bond linking the two glucose units is called a glycosidic linkage, indicated by the arrows in the following structures ... 

Cellulose is composed of D-glucose units linked by j8-l,4 glycosidic bonds. This bonding arrangement (like that in cellobiose) is rather rigid and very stable, giving cellulose desirable properties for a structural material. Figure 23-17 shows a partial structure of cellulose. 

The hydrogen bonding in cellobiose and methyl cellobioside as models for that in the celluloses. In the absence of crystal structure analyses of higher oligomers of 1 - 4-linked /5-glucopyranose, cellobiose is frequently used as a model for interpreting the X-ray fiber diffraction patterns of the celluloses, especially since the cellobiose unit is considered to be the repeating unit of the polysaccharide chain. 

Cellobiose, a degradation product of cellulose, contains two molecules of glucose linked by a j8( 1,4) glycosidic bond (Figure 7.28). Like maltose, whose structure is identical except for the direction of the glycosidic bond, cellobiose does not freely exist in nature. 

Fig. 8.—Two Possible Ways of Linking /3-D-Glucopyranose Residues, Both of Which Satisfy the Fiber Repeat of 10.3 A. (Structure A does not possess a twofold axis and could not yield cellobiose on hydrolysis.)...

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