Peptides are polymers (chains) of 50 or fewer amino acids that are joined together via peptide bonds. The difference between a peptide and a protein is their size, where proteins are made up of more than 50 amino acids. Peptides can have many different functions, such as signaling inside and between cells and organs.
How peptides are created
Peptides are most often formed via the so-called protein synthesis, where amino acids are linked to each other in an organized way via so-called peptide bonds. Peptides can also be created by cleaving proteins (proteins contain 51 or more amino acids in a chain) in the cell, or produced synthetically in a lab.
A tripeptide consists of three amino acid residues. R is the side chain from the first amino acid. R 'and R' ', respectively, are for the second and third amino acids.
A tripeptide consists of three amino acid residues. R is the side chain from the first amino acid. R 'and R', respectively, are for the second and third amino acids.Tripeptide (tri = 3). The peptide bond (-C (= O) NH-) is formed by a reaction between the carboxyl moiety of one amino acid and the amino moiety of another. After the amino acids have created a peptide, the former amino acids are called amino acid residues. In a peptide, the amino acid residue that has an amino group that is not attached to anything is called an N-terminal. The amino acid residue with a carboxyl group that is not attached to anything is called a C-terminal. There is only one N-terminus, and one C-terminus per peptide chain.
Different types of peptides
Peptides get slightly different names depending on how long they are:
Dipeptide: 2 amino acid residues
Tripeptide: 3 amino acid residues
Tetrapeptide: 4 amino acid residues
Pentapeptide: 5 amino acid residues
There are also some more general terms for peptides:
Oligopeptide: 2 to 20 amino acid residues
Polypeptide: Unspecified length (even longer than 50 amino acid residues).
Naming of peptides
The order in which the amino acid residues are linked plays a major role in the properties of the peptide. You start counting from the N-terminal when you name a peptide with a word formula. If we have a tripeptide (tri = 3) where valine (val, V) sits first and is N-terminal, Glycine (gly, G) sits in the middle, and lysine (lys, K) sits last and is C-terminal so the peptide is named as follows with three-letter codes:
Val - Gly - Light
Alternatively like this with one letter codes:
All three-letter codes and single-letter codes