10 Examples of Peptide Links

The peptide bonds are a specific type of link between a amino acid and another, which takes place through an amino group (-NH₂) in the first amino acid and a carboxyl group (-COOH) in the second, producing a covalent bond -CO-NH- and releasing a molecule of water. For example: oxytocin, vasopressin, leptin.

In this way a new molecule called peptide and that will be named after both amino acids. The peptide bond between a molecule of to the girl (provided by the -NH terminal₂) and another of serine (providing the -COOH terminal) is named as an alanyl-serine peptide.

This is one of the forms of bond that allow amino acids to be joined (by dehydration) to produce more complex structures (polypeptides) since a Once the link is obtained, it is possible to continue joining amino acids through the same process, starting from the carboxyl group terminal. In the same way, more complex structures such as polypeptides and protein. It is an extremely common procedure in living beings.

Properties of peptide bonds

Peptide bonds have certain features. For example, the established link is of the simple but shorter type: with characteristics of a double bond, such as stabilization by resonance. The latter prevents free turns around the bond (something common in this type of bond), which gives the peptide bond an unavoidable flat structure.

Similarly, peptide bonds can be degraded or broken by hydrolysis (addition of water), releasing an amount of energy in a very slow process. This process can be accelerated in the presence of catalysts acidic, basic or enzymatic.

Examples of peptide bonds

Any peptide is a perfect example of peptide bonds, as they are the result of this type of amino acid joining. Here are some of the most important:

1. Bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg). Composed of nine amino acids, this peptide is a drug that produces vasodilation and a drop in blood pressure, which is why it is used to treat hypertensive patients.
2. Oxytocin (Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly). Is a hormone produced by the hypothalamus and which performs neuromodulatory functions of the central nervous system and a vital role in the preparation of the female cervix during childbirth and of the breasts during lactation.
3. Glucagon (NH2-His-Ser-Gln-Gly-Thr-Phe-Thr-Ser-Asp-Tyr-Ser-Lys-Tyr-Leu-Asp-Ser-Arg-Arg-Ala-Gln-Asp-Phe-Val-Gln -Trp-Leu-Met-Asn-Thr-COOH). It is a peptide hormone of 29 amino acids that is synthesized in the pancreas and that intervenes in the metabolism of sugars.
4. Glutathione (L-γ-glutamyl-L-cysteinylglycine). It is a tripeptide of three amino acids: cysteine, glutamate, and glycine. Is the principal antioxidant cellular, which protects cells from free radicals and peroxides.
5. Vasopressin (NH₂-Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Arg-Gly-COOH). Segregated by the hypothalamus, it controls the reabsorption of water molecules from the urine, increases their concentration and plays a key role as a blood homeostatic regulator. It is a nine amino acid hormone.
6. Insulin. It is a polypeptide hormone made up of 51 amino acids, secreted by the pancreas to regulate the blood sugar cycle.
7. Prolactin. It is a peptide hormone that stimulates the production of milk in the maternal breasts. It is made up of a sequence of 198 amino acids.
8. Leptin. It is another peptide hormone that suppresses the feeling of hunger and is made up of a chain of 167 amino acids.
9. Gastrine. It is a peptide hormone that regulates the production of gastric juices in the stomach. It is made up of 14 amino acids.
10. Pepsin. It is a hormone composed of 326 amino acids, responsible for regulating the processes of digestion and absorption of food.

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