Glands in the mouth, stomach, pancreas and the small intestines produce digestive enzymes. There are four types of digestive enzymes. Each group is classified by the molecules upon which the enzyme acts. During digestion, all four subgroups work to break down food into nutrients that the cells can absorb.
Amylase
Amylase is a digestive enzyme secreted by the salivary and pancreatic glands. It functions to break down carbohydrates into a form that the body can use for energy. The main purpose of enzymes is to stimulate specific chemical reactions. Amylase brings about the hydrolysis of complex carbohydrates into maltose and glucose. The highest concentration of amylase is found in the pancreas. Amylase in the oral cavity has two roles. Its major role is the chemical conversion of starch to glucose. Secondly, it functions in the colonization and metabolism of oral bacteria. Amylase binds to bacteria. The bacteria-bound amylase converts starch to sugar. The bacteria component metabolizes the sugar to lactic acid. This leads to the formation of dental plaque.
Protease
Protease is a digestive enzyme secreted by the glands in the stomach and the pancreas. This type of enzyme is found in the gastric and the pancreatic juices. This enzyme has an important role in the digestive process. It functions to break down proteins into amino acids called peptides. Proteins are complex compounds composed of nitrogen-containing compounds called amino acids that are essential for every cell in the body. During digestion, protease, along with hydrochloric acid, break down the protein molecules into amino acids, which can be absorbed through the intestinal wall.
Lipase
Lipase is a digestive enzyme produced primarily in the pancreas but also found in the mouth and stomach. Its function is to break down fats, also known as lipids, into glycerol and fatty acids.(see reference 3) The initial digestive action of lipase begins inside the small intestines. The proper digestion of fats depends on emulsification. Fat molecules are large and present small surfaces for lipase to act upon. Bile aids lipase in the process of emulsification. Bile breaks fats into smaller molecules upon which pancreatic lipase can do its job. (see reference 4)
Nuclease
Nuclease is the fourth type of digestive enzyme and is secreted by the pancreas. Its function is to separate the bonds between the nucleotides of nucleic acids. DNA and RNA are two types of nucleic acids -- the building blocks of all living organisms. Nuclease targets nucleic acid to release nitrogen bases and simple sugars.
