Amylase breaks down carbohydrates. They’re called amylolytic enzymes. Carbohydrates include:
- Sucrose- a disaccharide commonly called cane sugar. Sucrase splits sucrose to glucose and fructose.
- Fructose- a monosaccharide found in fruit and honey.
- Lactose- a disaccharide found in milk. Lactase splits lactose to glucose and galactose.
- Starches- large polysaccharides found in nonanimal foods especially grains. Amylase splits starch to maltose, which is then split by maltase to glucose.
Amylase also breaks down glycogen, which is the storage form of glucose in animals including humans, which is analogous of starch in plants.
Amylase is a basic carbohydrase, which breaks down complex carbohydrates such as found in fruits, vegetables and legumes into simple sugars. Its therapeutic use is regulation of histamine, which is produced in cells in response to recognized invaders to the body. Histamine is produced in allergic reactions such as hayfever. Histamine is what causes hives, itchy watery eyes, sneezing and runny noses. Amylase is there to break down the histamine produced by the body in response to allergens such as pollen or dust mites. Some believe it may help the body identity the allergen as nonharmful so the body does not produce the histamine. Possibly amylase’s role could be both.
Alpha-amylase hydrolyses alpha-bonds of large alpha-linked polysaccharides such as starch as previously mentioned thus yielding glucose and maltose. It’s the major form of amylase found in humans and other mammals and is also found in seeds, which contain starch as a food reserve. Many fungi also secrete it.
Amylase is predominately found in pancreatic juice and saliva, although it’s found in many tissues, and each has its own isoform of human alpha-amylase. They can be separated in testing by using specific monoclonal antibodies.
Salivary amylase, also called ptyalin, breaks down starch into maltose and dextrin. The large starch molecules are broken down into soluble starches – amylodextrin, erythrodextrin achrodextrin – producing smaller starches an ultimately maltose. Salivary amylase is inactivated in the stomach by gastric acid.
There is a genetic variation in human salivary amylase. It appears that the salivary amylase gene has undergone duplication during evolution. The gene copy number is associated to evolutionary exposure to high starch diets. Perry, et al. published findings in an article “Diet and evolution of human amylase gene copy number variation”, in Nature Genetics (2007). They found an individual living in Japan had 14 copies of the amylase gene, while a Biaka individual had 6 copies. Biaka are rainforest hunter-gatherers who have a low starch diet.
Pancreatic alpha-amylase randomly cleaves the alpha (1-4) glycosidic linkages of amylose. This yields dextrin, maltotriose, and maltose.
To test for amylase is easier to perform than the one for lipase; therefore, it’s the primary test used to detect and monitor pancreatitis. Labs usually measure either pancreatic amylase or total amylase. Because of the small amount present it’s crucial to sample blood soon after a bout of pancreatic pain otherwise the kidneys will excrete it.
Increased plasma levels of alpha-amylase in humans are found in:
- Mumps because of inflammation of the salivary glands.
- Salivary trauma such as anaesthetic intubation.
- Pancreatitis because of damage to cells that produce the enzyme.
- Renal failure because of reduced excretion.
Pancreatitis usually produces total amylase readings ten times the upper limit of normal. Duodenal disease or renal failure produce 5 to 10 times the ULN and lower elevations are common in salivary gland disease.