Peptide Knowledge Center

A complete review of solution phase peptide synthesis

Peptide is a kind of bioactive substance related to various cell functions in organism. Its molecular structure is between amino acid and protein. It is a compound formed by the combination of various amino acids through peptide bond in a certain order.


Chemical peptide synthesis is considered to be a conventional and most widely used technology for peptide production, including solid phase and solution phase peptide synthesis.In 1963, Dr.Merrifield successfully developed the solid-phase peptide synthesis method. After continuous improvement, the solid-phase method has become a common technology in peptide and protein synthesis, showing the incomparable advantages of classical solution-phase synthesis,. However, in recent years, scientists have made some breakthroughs in the field of solution phase synthesis, which makes the liquid phase peptide synthesis technology still occupy a dominant position in some fields.


The solution phase peptide synthesis can be divided into two strategies: stepwise synthesis and segment ligation method. It can be used for the synthesis of various bioactive peptides.The stepwise synthesis method is simple and rapid, and can be used for the synthesis of various bioactive peptides.In recent years, the solution-phase segmented synthesis method is another major breakthrough in the field of peptide and protein synthesis, that is, peptide segments are spontaneously linked to growth peptides in solution according to their chemical specificity or chemical selectivity. Because the peptide contains a few amino acid residues, it has high purity and is easy to purify.


Native Chemical Ligation

The Native Chemical Ligation is the most simple and practical method for segment ligation. In 1994, Kent et al. added the C-terminal thioester peptide and the N-terminal Cys (cysteine) to phosphate buffer solution with pH 7.6 to obtain the peptide with Cys as the linking site.Using Native Chemical Ligation technology, Shin et al. synthesized glycoprotein with antibacterial activity; Tam et al. produced cyclic protein containing multiple Cys residues; Duhee et al. successfully synthesized a protein with 46 amino acid residues by two-stage and three-stage condensation; Regula et al. used this method synthesized proNPY which containing 69 oxoacid residues . Gapbor et al. synthesized the first semisynthetic serine protease SGT by this method.


Chemo and regioselective ligation

The Chemo and regioselective ligation method is a Cys site linking technique, in which 2-mercaptobenzyl is used as the auxiliary group to produce nucleophilic reaction with thioesters. The introduction of electronic groups can increase the nucleophilicity and electron concentration on the aromatic ring, so as to improve the speed limiting step, the rate of thioester exchange reaction and the sensitivity of auxiliary group to acid, which greatly speeds up the condensation speed between segments and is conducive to the removal of auxiliary groups.


The peptide segments condensed by chemical regioselective ligation method are non side chain protected fragments. In synthesis, strong acids such as HF must be used to remove the side chain protecting groups and resins. However, the peptide of the product is not stable to acid and is easily affected by strong acid, so it is difficult to synthesize N-terminal peptide.


Staudinger Ligation

Staudinger et al. Developed staudinger ligation method based on the biochemical azide reaction, which is the basic method of peptide condensation.Stoudenger Ligation is the reaction of C-terminal phosphine thioester with N-terminal azide to form phosphine imine, which is an intermediate with nucleophilic nitrogen. phosphine imine are rearranged within the molecule to obtain amide phosphine salt, which is hydrolyzed to obtain the target peptide and phosphine oxide.


Maarseveen et al. synthesized cyclic n-lactylaniline with 7-9 amino acid residues. Bardley et al. Have also verified that this method is an effective fragment condensation method, which broadens the field of fragment condensation.


The characteristics of solution phase peptide synthesis reaction :

1. In solution phase synthesis, all previous organic synthesis methods can be used without any limitation;

2. Homogeneous mixing of reactants and rapid movement of reactants increase the chance of reaction

3. In the case of a heating reaction, the heat energy is uniformly transferred through the dispersion of molecules in the solution

4. A large number of reactions can be achieved by controlling the size of the reactor and the amount of reactants

5. The reaction compounds can be purified and analyzed at each step.


Summary of solution phase peptide synthesis method

Compared with solid-phase synthesis, solution phase peptide synthesis has many advantages, such as more protective groups, lower cost, easy to scale up and so on. The disadvantage is that the synthesis range is small, normally used in the synthesis of less than 10 amino acids.


At present, Aurora company uses solid-phase synthesis, solution phase peptide synthesis, microwave synthesis technologies to provide customers with high-quality peptides.For more inquiry about peptide synthesis please get in touch with our customer center.