If you’ve ever come across proteins in one way or the other, then it means you are familiar with peptides too. Whereas proteins are large molecules made up of large chains of amino acids linked via amide bonds, peptides, on the other hand, are small chain proteins with not more than 50 amino acids in their molecular structure. Proteins are sometimes classified as large peptides (polypeptides). Note that the 50 amino acids rule is not rigid, but rather it is just enacted to create orderliness and assist in differentiate peptides and proteins. Sometimes smaller proteins like insulin are sometimes classified as peptides, and also large all american peptides like amyloid beta have been called proteins as well.
There is an extensive number of peptides that exists in the world, each with its own distinctive function and a large array of activities. Take for example peptide hormones that bind to protein receptor in other to activate it, and ensure it transmits signals to the cellular interior. Such signals can activate enzymes that change various cellular activities. A popular peptide hormone is Atrial natriuretic peptide (ANP), and it helps to decrease the volume of water, adipose, and sodium in the circulatory system, and in turn, this helps to decrease blood pressure. There are lots of neuropeptides, and each carries out the function of a transmitter. While some peptide transmitters are involved in modulating emotions, others act as perceive pain. Peptides antibiotics form part of the body defense mechanism, while hormones like adrenocorticotropin, act as neurotransmitters.