In biological research, polypeptides with a long sequence are usually used. For peptides with more than 60 amino acids in the sequence, gene expression and SDS-PAGE are generally used to obtain them. However, this method takes a long time and the final product separation effect is not good.
Challenges and solutions for long peptide synthesis
In the synthesis of long peptides, we are always faced with a problem, that is, the steric hindrance of the condensation reaction increases with the increase of the sequence in the synthesis, and the reaction time needs to be adjusted to make the reaction complete. However, the longer the reaction time, the more side effects are produced, and a portion of the target peptide is formed. Such residues – deficient peptide chains are key impurities produced in long peptide synthesis. Therefore, in the synthesis of long peptide, the key problem we must overcome is to explore the high quality reaction conditions and reaction methods, so as to make the amino acid condensation reaction more comprehensive and full. In addition, reduce the reaction time, because the longer the reaction time, the more uncontrollable side reactions, the more complex the by-products. Therefore, the following three points are summarized:
Microwave synthesis can be used: For some amino acids encountered in the synthesis process that are not easy to be integrated, microwave synthesis can be used. This method has remarkable results, and greatly reduces the reaction time, and reduces the formation of two key by-products.
Fragment synthesis method can be used: When some peptides are difficult to be synthesized by common synthesis methods and not easy to be purified, we can adopt the whole condensation of several amino acids in a certain segment of the peptide to the peptide chain as a whole. This method can also solve many problems in the synthesis.
Acylhydrazide synthesis can be used: acylhydrazide synthesis of peptides is a method of solid-phase synthesis of N-terminal Cys peptide and C-terminal polypeptide hydrazide chemical selective reaction between the formation of amide bonds to achieve peptide bonding method. Based on the position of Cys in the peptide chain, this method divides the whole peptide chain into multiple sequences and synthesizes them respectively. Finally, the target peptide is obtained through liquid-phase condensation reaction. This method not only greatly reduces the synthesis time of long peptide, but also significantly increases the purity of the final product.
Long peptide purification
The particularity of long peptides inevitably leads to complex components of crude peptides. Therefore, it is also a challenge to purify long peptides by HPLC. amyloid series of polypeptide purification process, absorbing a lot of experience and successfully used in the purification of long peptide. By adopting new equipment, mixing of multiple purification systems, repeated separation and other experience methods, the success rate of long peptide purification was greatly improved.
Post time: Apr-18-2023