Difference Between Amylopectin and Glycogen

Amylopectin and glucogen are two types of branched polysaccharides. The main difference between amylopectin and glycogen is that amylopectin is an insoluble form whereas glycogen is a soluble form. Amylopectin is one of the two types of starch, which is the main form of storage polysaccharides in plants. Glycogen is the main storage polysaccharide in animals. The 1,4-alpha glycosidic bonds form the linear chain of both amylopectin and glycogen while 1,6-alpha glycosidic bonds form the branches.

Key Areas Covered

1. What is Amylopectin
     – Definition, Structure, Role
2. What is Glycogen
     – Definition, Structure, Role
3. What are the Similarities Between Amylopectin and Glycogen
     – Outline of Common Features
4. What is the Difference Between Amylopectin and Glycogen
     – Comparison of Key Differences

Key Terms: Amylopectin, Glycogen, Glycosidic Bonds, Polysaccharide, Solubility

What is Amylopectin

Amylopectin refers to a branched-chain polysaccharide that composes D-glucose units polymerized via 1,4-alpha glycosidic bonds. 1,6-alpha glycosidic bonds form its branches. Amylopectin may consist of thousands of glucose molecules. The branching occurs at every 25-30 units of glucose. Amylopectin is insoluble in water. It gives less intense reddish brown color with iodine. The structure of amylopectin is shown in figure 1.

Figure 1: Amylopectin

Amylopectin is one of the two types of starch polysaccharides stored in plants and accounts for around 75% of the plant starch. Plant sources such as rice, corn, and potatoes are great sources of amylopectin.

What is Glycogen

Glycogen refers to the storage polysaccharide of animals and fungi. That is like starch in plants. 1,4-alpha glycosidic bonds form its linear chain while 1,6-alpha glycosidic bonds form the branches. Further, branching occurs in every 8-12 glucose molecules in the chain. Glycogen gives a reddish brown colour with iodine. The structure of glycogen is shown in figure 2.

Figure 2: Glycogen

Granules of glycogen occur in the cytosol of liver cells and muscle cells. The enzyme involved in glycogenolysis, the glycogen breakdown process, is glycogen phosphorylase. Glucagon is the hormone which stimulates glycogenolysis. Some glycogen-rich sources include livers, meat, and intestines of animals.

Similarities Between Amylopectin and Glycogen

• Both amylopectin and glycogen are branched polysaccharides.
• They both are made up of glucose monomers.
• Both contain 1,4-alpha glycosidic bonds and 1,6-alpha glycosidic bonds.

Difference Between Amylopectin and Glycogen

Definition

Amylopectin: a branched-chain polysaccharide found in plants.

Glycogen: a storage polysaccharide of animals and fungi.

Origin

Amylopectin: a storage polysaccharide in plants.

Glycogen: a storage polysaccharide in animals.

Formation

Amylopectin: formed by the polymerization of glucose.

Glycogen: formed by a combination of amylose and amylopectin.

Branching

Amylopectin: a branched polymer.

Glycogen: highly branched when compared to amylopectin.

Breakdown

Amylopectin: can be broken down by amylase.

Glycogen: hydrolyzed when it is dissolved in water.

Conclusion

Amylopectin and glycogen are two types of branched polysaccharides. Amylopectin is a type of starch and is one of the storage polysaccharides of plants. Glycogen is the storage polysaccharide in animals. Amylopectin is insoluble in water while glycogen is water-soluble. The main difference between amylopectin and glycogen is the solubility of each type of polysaccharide.

Reference:

“14.7: Polysaccharides.” Chemistry LibreTexts, Libretexts, 26 Oct. 2016, Available here.

Image Courtesy:

1. “Glycogen” Public Domain) via Commons Wikimedia
2. “Amylopectin chains” By Laghi.l – Own work (CC BY-SA 3.0) via Commons Wikimedia