Index
A peptide is the name assigned to short polymers of amino acids.
They are classified by the number of amino acid units in the chain, called amino acid residues .
Tripeptides have three amino acid residues, while tetrapeptides have four.
A polypeptide is formed when the chain of amino acid residues exceeds several dozen in length. A protein is a molecule made up of one or more polypeptide chains.
Proteins are unbranched polymers of amino acids attached from the head to the tail of the carboxyl group to the amino group, through the formation of covalent peptide bonds. The peptide backbone of a protein consists of the repeating sequence.
In a -N-Ca– C polypeptide chain, where N represents the nitrogen of the amide, Ca represents the carbon atom a of an amino acid in the polymer chain, and the final C is the carbonyl carbon of the amino acid.
This carbon in turn is linked to the amide N of the next amino acid, and so on. The unbranched polypeptide chain has two ends, an amino-terminal or N-terminal end and a carboxyl-terminal or C-terminal end.
Classification of tripeptides
Tripeptides have been classified into three categories: rigid, non-rigid, and intermediate, based on the relative structural stiffness between the C α and C β atoms in a tripeptide.
Many rigid tripeptides are made of hydrophobic residues, however there are tripeptides with polar side chains that form rigid structures.
Most of the tripeptides fall into the intermediate class, while very small numbers fall into the non-rigid class.
Structurally, all rigid tripeptides essentially form two structural classes, while intermediate and non-rigid tripeptides fall into one structural class.
This notion of stiffness and non-stiffness is designed to capture side chain interactions but not secondary structures.
Role of peptides in cosmetics
Peptides are generally used in anti-aging cosmetic products. Depending on their role, peptides can be:
- Inhibitor peptides of neurotransmitters: they act as biological competitors and relax the muscles and reduce facial wrinkles caused by the continuous movement of the muscles. Signal: these peptides produce hyaluronic acid that stimulates the production of collagen, elastin and keratin fibers and improves the level of hydration of the skin.
- Transporters: when metabolic processes are carried out, peptides are responsible for capturing and transporting metals necessary in the enzymatic synthesis of these processes. A practical example is the role of copper in the development and repair of collagen fibers in the skin.
Tripeptides tend to improve the production of collagen fibers that decline with age by acting as repair agents.
Tripeptides stimulate the synthesis of collagen, the epidermal growth factor, and have anti-inflammatory effects.
Examples of tripeptides
Some examples of tripeptides are:
- Eisenin with immunological activity. Eisenia bicyclisse is more commonly known as Arame.
- GHK-Cu is a peptide with essential immunological activity for wound healing and skin regeneration activity, used in anti-aging cosmetics and more commonly known as copper peptide.
- Glutathione an important antioxidant.
- Isoleucine-proline-proline found in dairy products is an inhibitor of angiotensin converting enzyme.
- Leupeptin is a protease inhibitor and also acts as a calpain inhibitor.
- Melanostatin is a peptide hormone produced in the hypothalamus that inhibits the release of the stimulating hormone from melanocytes.
- Ophthalmic acid is a glutathione analog isolated from the lens.
- Norophthalmic acid is another glutathione analog.
- Thyrotropin-releasing hormone stimulates the release of thyroid-stimulating hormone and prolactin in the anterior pituitary.
- L-cysteinyl-D-valine is a key precursor in penicillin and cephalosporin biosynthesis.
Structure of a tripptide
A tripeptide is a peptide that consists of three amino acids linked by peptide bonds.
A peptide is the name assigned to short polymers of amino acids. They are classified by the number of amino acid units in the chain, called amino acid residues.
Tripeptides have three amino acid residues, while tetrapeptides have four.
A polypeptide is formed when the chain of amino acid residues exceeds several dozen in length. A protein is a molecule made up of one or more polypeptide chains.
Peptide chains
Twenty amino acids form the building blocks for proteins.
Amino acids are chemically linked to form peptide bonds. You can call any chain of two or more amino acids a peptide. Therefore, a polypeptide is a type of peptide.
Furthermore, the dipeptides, tripeptides and tetrapeptides contain respectively two, three and four amino acids.
An oligopeptide is the general term for peptides that contain 12 to 20 amino acids. Peptides also rarely contain chains of more than 30 amino acids.
Peptides and polypeptides are proteins, but biochemists generally do not describe peptides and polypeptides using the generic term protein.
Also, biochemists typically only use the word protein when referring to large peptide molecules.
They could contain a single long chain of amino acids or consist of several chains of amino acids linked together.
An example of a large protein is hemoglobin. Red blood cells contain hemoglobin, and this protein contains four chains of amino acids.
