What is the Difference Between Alpha-Amylase and Alpha-Glucosidase

The key difference between alpha-amylase and alpha-glucosidase is that alpha-amylase is an enzyme that breaks down polysaccharides like starch and glycogen into disaccharides such as dextrin and maltose, while alpha-glucosidase is an enzyme that breaks down starch into glucose.

Starch is an important constituent of the human diet. It is the major storage polysaccharide of many economically important crops such as wheat, rice, maize, tapioca, and potato. Once the starch is consumed, it has to be digested in the digestive system. Alpha-amylase and alpha-glucosidase are two enzymes involved in starch digestion. Alpha-amylase converts starch into disaccharides, while alpha-glucosidase converts starch into glucose.

CONTENTS

1. Overview and Key Difference
2. What is Alpha-Amylase  
3. What is Alpha-Glucosidase
4. Similarities – Alpha-Amylase and Alpha-Glucosidase
5. Alpha-Amylase vs Alpha-Glucosidase in Tabular Form
6. Summary – Alpha-Amylase vs Alpha-Glucosidase

What is Alpha-Amylase?

Alpha-amylase is the major form of amylase found in humans and other mammals. Alpha-amylase is present in seeds containing starch as a food reserve and in fungi. It is a member of the glycoside hydrolase family 13. The basic function of this enzyme is to break down starch into disaccharides such as dextrin and maltose. It is mainly present in pancreatic juice and saliva. Each of these has its own isoform of human α-amylase. All these isoforms link to the chromosome 1p21 region.

Salivary amylase is found in saliva, and it breaks starch into maltose and dextrin. Salivary amylase is also known as ptyalin. It was named by a chemist named Jöns Jacob Berzelius. Salivary amylase first breaks insoluble starch molecules into soluble starches like amylodextrin, erythrodextrin, and achrodextrin. Later, these smaller starches are converted to maltose. Salivary amylase acts on linear α(1,4) glycosidic linkages. The optimum temperature for this enzyme is 5.6 – 6.9. The pancreatic α-amylase cleaves α(1-4) glycosidic linkages of amylose and yields dextrin, maltose, or maltotriose. Furthermore, the optimum pH of pancreatic alpha-amylase is 7. Alpha-amylase can be used as a biomarker to identify diseases like pancreatitis, salivary trauma, and mumps. Industrially, α-amylase is used in ethanol production, and medically it is used in degrading polymicrobial bacterial biofilms.

What is Alpha-Glucosidase?

Alpha–glucosidase is an enzyme that breaks down starch and disaccharides to glucose. It breaks terminal non-reducing (1→4)-linked α-glucose residues. This releases a single α-glucose molecule. Alpha–glucosidase is encoded by a gene called GAA, which is located in chromosome 17. The optimum pH of alpha–glucosidase is 4.3.

Alpha–glucosidase has many disease relavances. In glycogen storage disease type II, it causes alpha–glucosidase deficiency. Azoospermia is a disease that can be diagnosed by measurement of α-glucosidase activity in seminal plasma. Furthermore, alpha–glucosidase is industrially applied in carbohydrate research and in the food, feed, brewing, and biofuel industries. In addition, in medicine, α-glucosidase inhibitors are used to manage diabetic symptoms. Antivirals that have alpha-glucosidase inhibiting activity are also used to inhibit viruses such as HIV and HBV.

What are the Similarities Between Alpha-Amylase and Alpha-Glucosidase?

• Alpha-amylase and alpha-glucosidase are two enzymes involved in starch digestion.
• Both enzymes are proteins in nature.
• They act upon α(1-4) glycosidic linkages.
• Both enzymes are associated with diseases.
• They have industrial and medicinal uses.

What is the Difference Between Alpha-Amylase and Alpha-Glucosidase?

Alpha-amylase is an enzyme that breaks down polysaccharides like starch and glycogen into disaccharides such as dextrins and maltose, while alpha-glucosidase is an enzyme that breaks down starch into glucose. Thus, this is the key difference between alpha-amylase and alpha-glucosidase. Furthermore, alpha-amylase is encoded by AMY1 and AMY2 genes located in chromosome 1 in humans, while alpha-glucosidase is encoded by the GAA gene located in chromosome 17 in humans.

The below infographic presents the differences between alpha-amylase and alpha-glucosidase in tabular form for side-by-side comparison.

Summary – Alpha-Amylase vs Alpha-Glucosidase

Alpha-amylase and alpha-glucosidase are two enzymes involved in the digestion of starch present in the human diet. Both these enzymes act upon α(1-4) glycosidic linkages. However, alpha-amylase is an enzyme that breaks down polysaccharides like starch and glycogen into disaccharides such as dextrins and maltose, while alpha-glucosidase is an enzyme that breaks down starch into glucose. So, this summarizes the difference between alpha-amylase and alpha-glucosidase.

Reference:

1. “Alpha-Amylase.” An Overview | ScienceDirect Topics.
2. “Alpha-Glucosidase.” An Overview | ScienceDirect Topics.

Image Courtesy:

1. “Alpha-amylase” By PDB-101 – Own work (CC BY 4.0) via Commons Wikimedia
2. “Alpha-glucosidase in complex with maltose and NAD+” By Ccfreeny – Own work (CC BY-SA 3.0) via Commons Wikimedia