|Amylase is an enzyme that changes complex sugars (starches) into simple sugars during digestion. Amylase hydrolyzes starch, glycogen, and dextrin to form in all three instances glucose, maltose, and the limit-dextrins. Amylase is a digestive enzyme classified as a saccharidase (an enzyme that cleaves polysaccharides). It is mainly a constituent of pancreatic juice and saliva,
needed for the breakdown of long-chain carbohydrates (such as starch) into smaller units. Amylase is secreted by the salivary glands and the pancreas that helps in the digestion of carbohydrates. Amylase is primarily synthesized in acinar cells of the pancreas and is secreted into the pancreatic duct system, where it is transported to the intestinal tract. Additional amylase activity is found in the intestines, kidneys, and uterus. Amylase liquefies starches and converts them to maltose (sugar) and dextrins. Amylase is also synthesized in the fruit of many plants during ripening, causing them to become sweeter, and also during the germination of cereal grains. Grain amylase is key to the production of malt.
There are two isoforms of amylase: pancreatic and salivary amylase. They behave differently on isoelectric focusing, and can also be separated in testing by using specific monoclonal antibodies. Alpha-amylase (ptyalin) is produced by the salivary glands. This enzyme begins starch digestion in the mouth and continues to work in the stomach. Alpha-amylases catalyze the hydrolysis of complex carbohydrates into maltose and residual glucose. Ptyalin begins polysaccharide digestion in the mouth; the process is completed in the small intestine by the pancreatic amylase, sometimes called amylopsin. The amylase of malt digests barley starch to the disaccharides that are attacked by yeast in the fermentation process. Pancreatic amylase is secreted by the pancreas into the small intestine. This enzyme continues the starch digestion process.
Levels of amylase in the blood can be used to help diagnose and monitor diseases, such as diseases of the pancreas and salivary glands, or to determine whether the intestines have been damaged. Elevated levels may be a sign of pancreatitis. An ulcer that erodes tissue from the stomach and goes into the pancreas will cause amylase to spill into the blood. Abnormally high levels of amylase in the blood or urine may be found in patients with inflammation of the pancreas or salivary glands (mumps). Human amylase has an optimum pH of 7.2–7.4. Like most enzymes amylase is denatured by temperatures above 60°C. An amylase test measures the amount of this enzyme in a sample of blood taken from a vein or in a sample of urine collected over 2 or 24 hours. The normal range is 23 to 85 U/L. Some laboratories give a range of 40 to 140 U/L.