glucan 1,4-alpha-glucosidase activity

Definition

Target type: molecularfunction

Catalysis of the hydrolysis of terminal (1->4)-linked alpha-D-glucose residues successively from non-reducing ends of the chains with release of beta-D-glucose. [EC:3.2.1.3]

Glucan 1,4-alpha-glucosidase activity refers to the enzymatic hydrolysis of alpha-1,4-glucosidic linkages in glucans, which are polysaccharides composed of glucose units. This activity is crucial for the breakdown of starch and glycogen, two primary energy storage molecules in living organisms. The enzyme, often referred to as 1,4-alpha-glucosidase, cleaves the glycosidic bond between glucose residues, releasing individual glucose molecules or smaller oligosaccharides.

The specific mechanism of action involves the enzyme's active site, which typically contains an acidic amino acid residue. This residue, along with other catalytic groups, facilitates the nucleophilic attack of a water molecule on the glycosidic bond. The process results in the hydrolysis of the bond, yielding free glucose and a new reducing end on the remaining glucan chain.

This activity plays a vital role in various biological processes, including:

1. **Carbohydrate digestion:** 1,4-alpha-glucosidases, such as pancreatic alpha-amylase and intestinal sucrase-isomaltase, are responsible for breaking down dietary starch and glycogen into smaller, digestible units. These enzymes act in the digestive tract, allowing the body to absorb glucose as an energy source.

2. **Glycogenolysis:** In animals, the breakdown of glycogen stored in the liver and muscles is catalyzed by glycogen phosphorylase. This enzyme releases glucose-1-phosphate, which is further converted to glucose-6-phosphate by phosphoglucomutase. The glucose-6-phosphate can then enter glycolysis to generate energy.

3. **Sugar metabolism:** Glucan 1,4-alpha-glucosidases are involved in the regulation of blood glucose levels. For instance, the enzyme glucokinase, found in pancreatic beta cells, plays a crucial role in glucose sensing and insulin secretion.

4. **Plant development:** In plants, 1,4-alpha-glucosidases participate in the mobilization of starch reserves during germination and growth. They also contribute to the breakdown of starch during senescence and stress responses.

The molecular function of glucan 1,4-alpha-glucosidase activity is essential for maintaining energy homeostasis, regulating carbohydrate metabolism, and facilitating various biological processes in living organisms.'
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Proteins (2)

Compounds (42)