Glycogenolysis | Glycogen Breakdown | Glycogen Metabolism | Carbohydrate Metabolism | Biochemistry

This video provides a tutorial on glycogenolysis (glycogen breakdown). The alpha (1-4) glycosidic bonds between glucose monomers in glycogen chain are broken down by glycogen phosphorylase enzyme. This reaction occurs by phosphorylosis, wherein the inorganic phosphate is transferred to the OH group of C-1 position of terminal glucose molecule. The first step of glycogenolysis involves shortening of chain. In this step glycogen phosphorylase enzyme cleaves glucose residues one by one from nonreducing ends of glycogen and release glucose molecules as glucose-1-phosphate. The next step in glycogenolysis is the removal of branches. This is a two-step process and the reaction is catalyzed by debranching enzyme. Transferase activity of debranching enzyme transfers the branches and glucosidase activity of debranching enzyme hydrolyzed the single glucose residue as free glucose and the resulting glycogen chain is then processed by glycogen phosphorylase enzyme.

The following topics are covered in this lesson,

1. Glycogen structure
2. Glycogen breakdown
3. Cleavage of alpha (1-4)glycosidic bond
4. Steps involved in glycogenolysis
5. Shortening of glycogen chains
6. Removal of branches in glycogen chain
7. Limit dextrin
8. Debranching enzyme with 4:4 transferase activity
9. Debranching enzyme with 1:6 glucosidase activity
10. Release of glucose-1-phosphate from glycogen breakdown
11. Glycogenolysis in liver
12. Glycogenolysis in muscle