What are Peptides? Reasons why Peptides are so Popular.

What are peptides?

What are peptides? Peptides are short amino acid chains that are connected together. If only two amino acids are present then the peptide is a dipeptide. There are also tripeptides, tetrapeptides, etc. If the number of amino acids in the chain exceeds around ten or so, these compounds are considered polypeptides. These are larger molecules. There’s no single accepted size at which a large polypeptide becomes a small protein, but polypeptides usually have a molecular weight in the range of few thousand units, whereas proteins have molecular weights in the tens of thousands of units.

Depending on which amino acids are involved, between seven and ten amino acids add up to the molecular weight of about 1000 units.

In the diet, protein molecules are digested by enzymes (which are specialized proteins themselves), that break down the proteins into smaller and smaller chain lengths, the breakage occurs at the peptide bonds. Hence, peptides and amino acids are the final protein derived materials from the digestive enzymatic cleavage process. Amino acids are the main protein breakdown component ingested from the gut, but some di-and tri-peptides are also absorbed, the cells lining the small intestine have different carrier structures to transport these small peptides from the lumen to the blood.

Polypeptide Hormones:

Polypeptides regulate or activate a large number of body functions, operating near or at a distance from the location they are produced and released at.  Larger polypeptides and proteins typically fold to form unique three-dimensional shapes (which determine their actions in the body at the cellular level). Smaller polypeptides are not so structurally limited by specific three-dimensional shapes. For example, oxytocin and vasopressin, have about one thousand different conformations, all in complex equilibrium with one another. Therefore, how is it that they precisely bind to their receptors, with the same shape and charge distribution requirements? The response is that some part of the polypeptide binds to the receptor while the neighbouring parts turn and rotate until it meets the correct shape. The polypeptides thus use a’ zipper’ system for attachment to membrane receptors. Larger peptides of common interest include human growth hormone (HGH), CJC-1295, MOD-GRF 1-29, Melanotan II, GHRP-2, GHRP-6, Ipamorelin, Hexarelin, and HGH Fragment 176-191.


The neurons contain several different peptides, released along with other neurotransmitters. Some peptides that were originally identified as hormones, thought to be produced at a particular site and acting at certain’ target’ sites, were more recently found to be produced elsewhere as well, and have other functions, and thus for different purposes, the body uses the same peptide. For example, this is true of cholecystokinin (CCK), a polypeptide of 33 amino acids known for many decades as a hormone that originated in the duodenum and caused the gall bladder to empty. In summary, many peptides discovered outside the brain, are also now recognized as neuroactive.


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Disclaimer: All of the content in this article is summarized from third party sources. ELV Bioscience makes no health or medical claims associated with our products. Our products are sold for research and laboratory use only.

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