Alpha-amylase (α-Amylase)

Alpha-amylase is a calcium-dependent enzyme that catalyzes the endohydrolysis of internal α-(1→4) glycosidic bonds in starches and related polysaccharides, producing smaller sugars like maltose and dextrins. It is widely distributed across animals (notably humans), plants, fungi, and bacteria. In humans, two main forms exist—salivary alpha-amylase initiates starch digestion in the mouth while pancreatic alpha-amylase continues this process in the small intestine. Structurally, it features a characteristic three-domain architecture with an eight-stranded α/β barrel catalytic domain containing key acidic residues at its active site; calcium ions stabilize its structure. Alpha-amylases are essential for energy metabolism from complex carbohydrates and have major industrial applications including food processing and biotechnology. Clinically relevant inhibitors are used to manage type 2 diabetes by slowing carbohydrate absorption from food.

Other names

1,4-α-D-glucan glucanohydrolaseGlycogenaseSalivary amylase (for the salivary isoform)Pancreatic amylase (for the pancreatic isoform)EC 3.2.1.1

Drugs such as acarbose inhibit alpha-amylase by binding to its active site, thereby blocking the hydrolysis of dietary starch into absorbable sugars and reducing postprandial blood glucose spikes.