Synthesis of a peptide is characterized as the formation of a peptide bond between two amino acids. While the definition of a peptide is not conclusive, it usually refers to flexible chains of up to 30-50 amino acids.
The capability to form peptide bonds to link amino acids together is more than 100 years old, although the first peptides to be synthesized, such as insulin, did not occur until the 1950s and 60s, indicating the problematic task of chemically producing chains of amino acids.
In the last 50 years, improvements in protein synthesis chemistry and methods have developed to the point where Synthesis of a peptide is a common approach in even high-quantity biological research and product and drug advances.
The advantage of synthesis of a peptide approaches is that besides having the capacity to make peptides that originate in biological specimens, ingenuity and resourcefulness can be tapped to generate distinctive peptides to enhance a desired biological response or other result.
Liquid-phase synthesis of a peptide was the original approach to peptide synthesis, but has since been replaced in most laboratories by solid-phase peptide synthesis. It does, however, retain practicality in large-scale production of peptides for industrial purposes.
Solid-phase synthesis of a peptide caused a major swing within the peptide synthesis community and it is now the customary method for synthesizing peptides and proteins in the lab. Solid-phase synthesis of a peptide allows for the synthesis of natural peptides which are not easy to express in bacteria, the absorption of unnatural amino acids, peptide/protein backbone alteration, and the synthesis of D-proteins, which consist of D-amino acids.
Because amino acids have numerous reactive groups, synthesis of a peptide must be cautiously performed to avoid side reactions that can reduce the length and cause splitting of the peptide chain. To enhance peptide formation with few side reactions, chemical groups have been established that bind to the amino acid reactive groups and block the functional group from nonspecific reaction.