In organic chemistry, peptide synthesis is the creation of peptides, which are organic compounds in which more than two amino acids bind via peptide bonds.
Peptides are synthesized by combining the carboxyl group of one amino acid with the amino group of another. During peptide synthesis, one side of the amino acids has to be protected to keep the acids from reacting with themselves.
There are two types of methods for obtaining polypeptides. One is the stepwise elongation method, in which the amino acids are connected step-by-step in turn.
The other is the fragment condensation method, in which peptide fragments are coupled to each other. Although the former can elongate the peptide chain without racemization, the yield drops if only it is used. Fragment condensation is better than stepwise elongation for synthesizing sophisticated long peptides, but its use must be restricted in order to protect the racemization.
There are two ways of synthesizing polypeptides, too. One is liquid-phase peptide synthesis, and the other is solid-phase peptide synthesis. When the former is utilized, the product can usually be purified halfway, yet time, effort, skill, and experience are necessary. When the latter is used, less time and effort are necessary for the synthesis because the experimental operation is simpler, but it is impossible to purify the peptide during the process.
The choice of which method to use is left to the person who synthesizes the peptide.