Principles of Biochemistry

4.2.5 Amino acids and peptides

 A peptide consists of two or more amino acids linked by a peptide bond formed between the carboxyl (-COOH) group of one amino acid and the amino (-NH₂) group of another amino acid releasing one molecule of water. Two amino acids are thus linked to form a dipeptide.

 

If three amino acids are thus linked, it is a tripeptide and if many amino acids are liked they are called polypeptide. The term oligopeptide refers to a chain of 4 to 10 amino acids where as a polypeptide containing more than 10 amino acids are called proteins. These polypeptide chains twist, fold or coil into different shapes in forming the proteins.