Long peptide synthesis

Long peptide synthesis

In modern biological research, polypeptides with relatively long sequences are often used. For polypeptides containing more than 60AA in the sequence, gene expression and SDS-PAGE are usually used to obtain them, but this method has a long cycle and poor separation effect of the final product, so solid-phase growth peptide synthesis technology has become a need. After a long period of exploration and accumulation, the synthesis process and method have been continuously optimized, and the problems of difficult synthesis, purification, low success rate and low yield of long peptide have been solved.

Analysis of long peptide synthesis

In the synthesis, the steric hindrance of the condensation reaction increases with the increase of the sequence, and the reaction time needs to be extended in order to complete the reaction. However, with the extension of the reaction time, more side reactions will be generated, and some deficient target peptides will be generated. These deficient peptide chains are also the main impurities produced in the synthesis process of long peptides. Therefore, we have to explore better reaction conditions and methods to make the amino acid condensation reaction more fully and thoroughly, and shorten the reaction time. In addition to the use of high-quality condensation reagents. We have summarized the following experiences:

1. Accurately and flexibly control the reaction time to reduce by-products.
2. Microwave synthesis method: microwave synthesis method is suitable for some polypeptides containing amino acids that are difficult to condenate, and the method has significant effects and greatly reduces the reaction time.
3. Fragment synthesis method: When some peptides are difficult to synthesize and purify by conventional synthesis methods, we will also use the condensation of several amino acids in a certain segment of the peptide to condense into the peptide chain as a whole.
4. Using hydrazide synthesis method: The method of synthesizing polypeptides by hydrazide is the method of chemically selective reaction between N-terminal Cys polypeptide synthesized in solid phase and C-terminal polypeptidyl hydrazide to form an amide bond and realize the polypeptide connection. According to the location of Cys in the peptide chain, the whole peptide chain is divided into multiple sequences and synthesized respectively. Finally, the target peptide is obtained through liquid phase condensation reaction. This method not only greatly reduces the synthesis time, but also significantly improves the purity of the final product, so it is widely applicable to the synthesis of long chain polypeptides containing Cys.

Purification of long peptides

The particularity of long peptides inevitably leads to the complex components of the final crude peptides, so it is also a challenge to purify long peptides by HPLC. We have gained rich experience in a series of long peptide purification processes. We have greatly improved the purity of long peptides by using advanced instruments, mixing of multiple purification systems, repeated separation and other means.