An amylase protein is a type of enzyme that is involved in the digestion of complex carbohydrates. In particular, it breaks down large molecules of starch and glycogen into their smaller sugar subunits of maltose and glucose. There are three different types of amylase proteins, which are alpha amylase, beta amylase and gamma amylase.
Mammals, plants, fungi and some bacteria all produce an amylase protein. Alpha amylase protein is the form of amylase that is found within humans and other mammals. It is also found within plants, bacteria and fungi. Beta amylase is primarily produced by bacteria, fungi and plants, while gamma amylase is found only in highly acidic environments.
Within the human digestive system, this protein is found within the saliva in the mouth and the pancreatic juices that are secreted into the duodenum of the small intestine. The amylase protein found within the mouth is referred to as ptyalin or salivary amylase. It begins the digestion of starch while the food is in the mouth. Salivary amylase breaks down starch into smaller molecules by breaking specific bonds found within the starch molecule.
During the digestion of starch by salivary amylase, the enzyme breaks a type of bond called a linear alpha (1,4) glycosidic bond. These types of bonds are covalent bonds that form between a carbohydrate molecule, like glucose, and another molecule, which may or may not be a carbohydrate. In this case, the enzyme is working on the bond between the first carbon of one molecule and the fourth carbon of the other. The acidic environment of the stomach inactivates and breaks down the salivary amylase protein.
Within the stomach, food is combined with gastric juices to produce a creamy mixture called chyme. It passes from the stomach into the duodenum of the small intestine so that digestion can continue. The majority of digestion occurs within the duodenum so that food is broken into small molecules that can be absorbed into the body when it passes into the ileum of the small intestine.
When chyme enters the duodenum, it stimulates the production and release of digestive enzymes. A number of different digestive enzymes are made in the pancreas, including pancreatic amylase protein. This enzyme continues the work that was begun in the mouth by the salivary amylase protein.
Pancreatic amylase further digests the larger carbohydrate molecules, turning them into maltose, a type of sugar. Maltose is a disaccharide, meaning it has two glucose molecules. It is acted on by maltase to produce two glucose molecules. These molecules are the end result of carbohydrate digestion, and are then absorbed into the bloodstream.