What Are the Main Functions of Peptides?

Peptides are biological molecules that are made up of amino acids. A peptide is a chain of covalently bonded amino acids that can consist of anywhere between 2 and about 40 amino acids in length, which can then be bonded together to form proteins in the body. The function that a peptide carries out is dependent on which types of amino acids are involved in the chain. While peptides are involved in a number of ways in the body's chemistry, they can best be classified by their functions.

Hormones are types of peptides that carry signals between glands and cells. These peptides control body functions such as sleep and blood sugar regulation. They are made by the endocrine glands, as well as in the kidneys, stomach, intestine and liver. Insulin, human growth hormone, bradykinins, gastrins and oxytocins are peptides that are common hormones.

Neuropeptides are produced in the brain and are found in neural tissues. These peptides function as an extension of the neurosystem throughout the body acting as signals and regulators in processes that are triggered from places in the brain. Endorphins are common forms of neuropeptides.

Alkaloids are peptides that are commonly used in the development of defense mechanisms in types of fungi, plants and small animals such as shellfish. Ergotamine, pandamine and dynorphin are types of alkaloid peptides.

Antibiotics are peptides that stop the growth of microorganisms in the body. They are frequently used in medicine to kill disease-causing bacteria.

When peptide chains reach a long length, they form proteins that, in turn, are the building blocks for parts of the human body and animal bodies. Keratin, a protein, is a part of hair and nails in humans and makes up the claws, horns, feathers, scales and hooves of animals. Collagen, another protein made from peptides, is a part of tendons and ligaments, as well as tooth enamel and bones.