Cellobiose

A disaccharide consisting of two glucose molecules

Overview

Skeletal structure of cellobiose

Cellobiose is a disaccharide consisting of two glucose molecules linked by a _(1_4) glycosidic bond. It is a product of the enzymatic breakdown of cellulose, a major component of the cell walls of plants. Cellobiose is an important intermediate in the biochemical conversion of cellulose to glucose.

Structure

Cellobiose is composed of two D-glucose units. The linkage between the glucose units is a _(1_4) bond, which is a type of glycosidic bond. This bond is resistant to hydrolysis by most amylase enzymes, which is why cellulose is not digestible by humans.

Properties

Cellobiose is a reducing sugar, meaning it has a free aldehyde or ketone group capable of acting as a reducing agent. It is soluble in water and has a sweet taste. The presence of the _(1_4) linkage gives cellobiose distinct properties compared to other disaccharides like maltose, which has an _(1_4) linkage.

Biological Role

In nature, cellobiose is an intermediate in the degradation of cellulose by cellulase enzymes. These enzymes are produced by certain bacteria, fungi, and protozoa that can digest cellulose. The breakdown of cellulose to cellobiose and then to glucose is a crucial step in the carbon cycle, allowing the conversion of plant biomass into usable energy forms.

Industrial Applications

Cellobiose is used in research to study the enzymatic breakdown of cellulose. It is also used in the production of biofuels, where cellulose is converted to glucose and then fermented to produce ethanol.

Related pages

• Cellulose
• Glucose
• Disaccharide
• Glycosidic bond
• Cellulase