Peptide synthesis is a solid-phase synthesis sequence, generally from C-terminal (ammonia terminal) to N-terminal (carboxyl terminal). In the past, peptide synthesis was carried out in solution, which is called liquid phase synthesis. Since Merrifield successfully developed the solid-phase peptide synthesis method in 1963, through continuous improvement and perfection, today, the solid-phase method has become a common technology in peptide and protein synthesis, showing advantages over the classical liquid-phase synthesis method, which greatly reduces the difficulty of product purification in each step.
Generally, the peptides synthesis is divided into two types: solid-phase synthesis and liquid-phase peptide synthesis.
Based on the principle of solid phase reaction, the polypeptide synthesizer continuously adds, reacts and synthesizes amino acids according to the known sequence (sequence, generally from c-carboxyl end to N-amino end) in a closed explosion-proof glass reactor, and finally obtains the polypeptide carrier. Solid phase synthesis method greatly reduces the difficulty of product purification in each step. In order to prevent side reactions, the side chains of amino acids participating in the reaction are protected. The carboxyl end is free and must be activated before the reaction.
1) Deprotection: Resins protected by Fmoc must use an alkaline solvent (piperidine) to remove the protecting group of the amino group.
2) Activation and crosslinking: the carboxyl group of the next amino acid is activated by an activator. The activated monomer reacts with free amino groups to form peptide bonds. In this step, a large amount of super concentration reagent is used to complete the reaction. Cycle: the two-step reaction cycles repeatedly until the synthesis is completed.
3) Elution and deprotection: the polypeptide is eluted from the column, and its protective group is eluted and deprotected by a deprotection agent (TFA).