amylase

Amylase is a digestive enzyme that catalyzes the hydrolysis of starch into smaller carbohydrates, primarily maltose and glucose. It belongs to the glycoside hydrolase family of enzymes. In humans, amylase is produced mainly by the salivary glands and the pancreas and is found in saliva and pancreatic juice.

The major form in humans is alpha-amylase, with two main isoforms: salivary amylase and pancreatic amylase. Beta-amylases occur in plants, bacteria, and fungi and typically release maltose from the non-reducing end of starch, whereas gamma-amylases (glucoamylases) from some microorganisms can release glucose from starch by acting on both alpha-1,4 and alpha-1,6 linkages. The different forms vary in optimal pH, temperature, and substrate specificity.

Mechanism: Amylases cleave internal (endo-type) alpha-1,4-glycosidic bonds, producing shorter polysaccharides such as dextrins, maltose, and glucose. They do not typically hydrolyze the branch points (alpha-1,6 bonds) as efficiently as glycogen-debranching enzymes; other enzymes complete the breakdown to glucose. Calcium ions help stabilize some amylases; many are secreted along with other digestive components.

Physiology and clinical relevance: In humans, salivary amylase begins carbohydrate digestion in the mouth; pancreatic amylase continues digestion in the small intestine. Serum amylase measurements are used in clinical settings as part of the evaluation for suspected pancreatitis or salivary gland disorders; levels may be elevated in pancreatic disease, salivary gland inflammation, or ductal obstruction.

Industrial and ecological roles: Amylases are widely used in industry to convert starch to sugars in processes such as bread making, brewing, and production of sweeteners; thermostable amylases from microbes are common in detergents and biofuel production.