Amylases are enzymes that break down complex carbohydrates, specifically starches, into simpler sugars. This process, known as hydrolysis, uses water to split chemical bonds, converting large starch molecules into smaller sugar units.
Different Kinds of Amylases and Where They Are Found
There are three main types of amylases: alpha, beta, and gamma. Alpha-amylase, found in humans, animals, plants, and microorganisms, acts randomly on the internal alpha-1,4 glycosidic bonds within starch chains, yielding maltose, maltotriose, and dextrins. This random action allows for rapid starch breakdown.
Beta-amylase is primarily found in plants and microbes, where it cleaves off maltose units from the non-reducing end of starch molecules, specifically the second alpha-1,4 glycosidic bond. This type is particularly relevant in fruit ripening, contributing to their sweet taste as starch converts to maltose.
Gamma-amylase, present in both plants and animals, works from the non-reducing end of the starch molecule, breaking down both alpha-1,4 and alpha-1,6 glycosidic bonds to release individual glucose molecules. It exhibits an acidic optimal pH, usually around 3.0.
Amylases and Digestion
In humans, alpha-amylase is the predominant type, secreted by the salivary glands and the pancreas. Amylases are important for the human digestive system, beginning carbohydrate breakdown in the mouth. Salivary amylase, also known as ptyalin, is released by the salivary glands and starts hydrolyzing starches as soon as food is chewed. This initial breakdown converts complex carbohydrates into smaller sugars like maltose and maltotriose. The enzyme functions optimally in a pH range of 6.7 to 7.0.
As partially digested food moves from the mouth to the stomach, the acidic environment largely deactivates salivary amylase. Starch digestion then continues in the small intestine, where pancreatic amylase takes over. The pancreas secretes this enzyme into the small intestine, specifically the duodenum, where it further breaks down remaining complex carbohydrates and dextrins into maltose and other disaccharides.
This breakdown is important because starches are too large to be absorbed into the bloodstream. The resulting simpler sugars, such as maltose, are then further processed by other enzymes in the small intestine into glucose, the body’s primary source of energy. This ensures carbohydrates from food are readily absorbed and utilized by the body.
Amylase Levels and Health
Amylase levels can be measured in blood or urine to help assess the function of organs that produce the enzyme, such as the pancreas and salivary glands. A normal range for amylase in a blood sample is typically between 30 to 110 units per liter (U/L), though these values can vary slightly between laboratories. In a urine sample, the normal range is approximately 2.6 to 21.2 international units per hour (IU/h).
Elevated amylase levels in the blood or urine often indicate a health issue, particularly problems with the pancreas, such as acute pancreatitis, which is inflammation of the pancreas. High levels can also suggest a blockage in a pancreatic duct, pancreatic cancer, or issues with salivary glands, like mumps.
Conversely, lower than normal amylase levels are less common but might point to chronic pancreatitis, kidney disease, liver disease, or cystic fibrosis. Abnormal amylase levels are indicators and require further medical evaluation for a precise diagnosis.