What Is the Difference between Amylase and Amylose?

Jillian O Keeffe

Amylose is a molecule found in some foods, and is one component of starch. Amylase, on the other hand, is an enzyme that breaks down starch into smaller pieces. As starch is a significant source of energy in the human body, the interaction between amylase and amylose plays a useful role in metabolism of food. Sources of amylose include potatoes, pasta and bread, and the body produces amylase naturally in saliva and in pancreatic juices.

Amylase is an enzyme that breaks down starch and it is secreted in saliva.
Amylase is an enzyme that breaks down starch and it is secreted in saliva.

Starch is a form of carbohydrate, and it is present in a variety of plants. As starch contains useful energy for metabolism, animals and microbes like to eat starchy foods. Basically, starch is a collection of glucose molecules attached to each other, and scientists divide starch into two types of collections of glucose, which are amylose and amylopectin.

The pancreas contains alpha amylase.
The pancreas contains alpha amylase.

Amylopectin is a large subunit molecule, which contains up to about 2 million glucose molecules. It is composed of arrangements of about 30 glucose units stuck together with specific bonds called alpha (1-4) glycosidic bonds. Each of these little groupings is then stuck together by alpha (1-6) glyosidic bonds.

Although much smaller than amylopectin, amylose subunits still contain glucose molecules up to a maximum of about 20,000 glucoses per amylose. These molecules are held together by alpha (1-4) glycosidic bonds. Each amylose is a straight chain of glucoses, which bends itself into a helix form, whereas amylopectin is a chain with branches off it.

Each of the bonds holding the starch molecules together contains energy, and animals and microbes can use this energy to keep their own bodies running. Over time, evolution caused these types of organisms to develop an ability to break down amylose in order to get at this energy. All animals who eat starch produce amylase in the pancreas, and some also produce it in the salivary glands. In the case of humans, amylase and amylose interactions begin in the mouth when food is exposed to saliva, and the enzymatic breakdown continues when the enzyme is released from the pancreas into the first part of the small intestine after the food moves through the stomach.

The specific interaction between amylase and amylose occurs because the enzyme only cuts alpha (1-4) glycosidic bonds. It is unable to cut alpha (1-6) glycosidic bonds. After the starch is exposed to amylase, therefore, the enzyme breaks down the starch at specific bonds, chopping up amylose and amylopectin into small pieces. These pieces turn out to be maltose, maltotriose, and limit dextrins which contain two, three and about five glucoses each. Only the limit dextrins contain the alpha (1-6) glycosidic bond branches that originated in amylopectin, whereas the other two breakdown products are structured in straight chains.

Once amylase and amylose have come into contact and the enzyme has performed its function, another set of enzymes takes over. These enzymes are called the sucrase-isomaltase complex, and they break down the maltose, maltotriose and limit dextrins into individual glucose units. The glucoses then move into the body and are used for energy in cell processes.

Amylase is an enzyme found naturally in the digestive tract.
Amylase is an enzyme found naturally in the digestive tract.

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