propose-the-plausible-structure-of-the-disaccharide-that-contains-two-cyclic-d-g

Question

Propose the plausible β structure of the disaccharide that contains two cyclic D-galactose sugars that are linked via the β-1,4 glycosidic bond. Explain why this disaccharide is a reducing sugar, while the sugar below is not reducing sugar.

Structures of methyl α-D-talose and methyl β-D-talose.

Accepted Answer

Disaccharide structure with two D-galactose units, highlighting the glycosidic bond.

This disaccharide is a reducing sugar because it has a cyclic hemiacetal group that can be hydrolyzed into a straight-chain saccharide, while the given monosaccharides are nonreducing acetals.

Answer

Disaccharide structure of two D-galactose sugars linked by a β-1,4 glycosidic bond.

This disaccharide is a reducing sugar because it is connected via the β-1,4 glycosidic bond, while the given monosaccharides are nonreducing because there is no β-1,4 glycosidic bond.

Answer

Disaccharide structure showing two cyclic D-galactose units linked by a glycosidic bond.

This disaccharide is a reducing sugar because, by nature, disaccharides are reducing sugars, while the given monosaccharides are nonreducing sugars.

Answer

Disaccharide structure of two D-galactose sugars, emphasizing the β-1,4 glycosidic bond.

This disaccharide is a reducing sugar because it has a cyclic acetal group that can be hydrolyzed into a straight-chain saccharide, while the given monosaccharides are nonreducing hemiacetals.