Glycogenolysis

Is the catabolism of glycogen by removal of a glucose monomer through cleavage with inorganic phosphate to produce glucose-1-phosphate.

The breakdown of glycogen.

The breakdown of glycogen to glucose for use as a metabolic fuel and to maintain the normal blood concentration of glucose in the fasting state. Stimulated by the hormones glucagon and adrenaline.

Body’s breakdown of glycogen to glucose.

The process by which stored glycogen is broken down (hydrolyzed) to provide glucose.

Hydrolysis of glycogen to glucose-6-phosphate or to glucose, glycogenolytic.

The process by which glycogen is broken down to form glucose.

The process of releasing glucose from glycogen. Glycogenolysis is a carefully controlled series of reactions referred to as the glycogen cascade. It is called a cascade because of the stepwise changes in activation states of the enzymes involved. To release glucose for oxidation by the glycogenolytic pathway, the glycogen must be phosphorylated. This is accomplished by the enzyme glycogen phosphorylase. Glycogen phosphorylase exists in the cell in an inactive form (glycogen phosphorylase b) and is activated to its active form (glycogen phosphorylase a) by the enzyme phosphorylase b kinase. In turn, this kinase also exists in an inactive form, which is activated by the calcium-dependent enzyme, protein kinase, and active cAMP-dependent protein kinase. Each of these activations requires a molecule of ATP. Lastly, the cAMP-dependent protein kinase must have cAMP for its activation. This cAMP is generated from ATP by the enzyme adenylate cyclase, which, in itself, is inactive unless stimulated by a hormone such as epinephrine, thyroxine, or glucagon. As can be seen, this cascade of activation is energy dependent, with three molecules of ATP needed to get the process started. Once started, the glycolytic pathway will replenish the ATP needed initially as well as provide a further supply of ATP to provide needed energy. As mentioned earlier, the liver and muscle differ in the use of glycogen. This also affects how ATP is generated within the glycogen-containing cell and how much is generated by cells that do not store glycogen.

Conversion of glycogen into glucose in the liver and skeletal muscles.

A biochemical process, occurring chiefly in the liver and in muscle, by which glycogen is broken down into glucose- 1 -phosphate. Glycogenolysis forms the first stage of glycolysis.

Conversion of glycogen into glucose in the liver and muscles.

The biochemical reaction that entails the hydrolysis of glycogen into its constituent glucose units is commonly known as glycogenolysis.