Phage display technology is an in vitro screening technology that can screen target peptides from a large number of peptide libraries and display the peptides on the surface of phages. The phage currently widely used for display is the M13 phage display system, which consists of 5 capsid proteins. The function of the capsid protein pⅢ is mainly screening. The target polypeptide gene can be inserted into pⅢ, and its applicable vector range is also very wide. In 1985, phage display technology was created. As a technology for studying antigenic epitopes, phage display mainly uses genetic engineering technology to insert foreign genes into phage capsid proteins, so that the polypeptides encoded by foreign genes can be displayed as fusion proteins, and their own structure and activity do not change. After that, multiple rounds of screening are used to select highly specific antibodies or peptides that can bind to target molecules. In 1990, a random 6-peptide library based on phage display technology was created. After years of development, phage display technology has been used in addition to studying antigenic epitopes. It has also been applied in the fields of cell signal transduction, protein recognition sites, and drug development. With the widespread use of phage display technology, many diseases are identified through phage display technology. For example, through the phage random 12-peptide library, an antigenic short peptide related to ankylosing spondylitis was discovered. In the serum of patients with colon cancer, a peptide that may be a marker for colon cancer was also discovered through phage display technology. The capacity of the peptide library established based on phage display technology is as high as billions. In terms of screening peptide markers, phage display peptide libraries have the advantages of fast, relatively low cost, and large library capacity. By screening phage peptides that bind to specific antigens, new antibodies can be developed or existing antibodies can be improved. Phage display peptides can also be used for vaccine development, cancer diagnosis, and biosensor development.

Classification of Phage Display Peptide Libraries:

There are many categories of phage display peptide libraries, which can be divided according to the type of phage, the type of vector, and the type of library. According to the different types of phages, phage display peptide libraries are divided into M13 phage display system, T7 phage display system, T4 phage, λ phage display system, etc. Among them, the M13 phage display system includes the blue-white system and the auxiliary phage system. The blue-white system uses genetic engineering technology to insert reporter genes, such as the lacZ gene, into the phage vector. When the exogenous gene is inserted and can be expressed, the expression of the reporter gene will be disturbed, and white colonies will be formed in the host bacteria. When the inserted exogenous gene is not correctly expressed, the expression of the reporter gene will not be disturbed, and blue colonies will be formed in the host bacteria. The blue-white system is conducive to the rapid screening of phages containing exogenous genes. The auxiliary phage system is mainly used to support the synthesis and screening of phage display peptide libraries. It can provide the gene products necessary for phage display technology, such as the proteins required for phage replication and packaging, to ensure the normal operation of the phage display system. The T7 phage display system can display peptides or proteins in high copies and can be used for the screening of proteins with different molecular weights and affinities.

Fig. 1 M13 phage display system schematic diagram

The vectors of phage display peptide library include phage vector and phagemid vector. Phage vector can produce infectious phage particles, which can be used to display larger polypeptides or protein fragments. Phagemid is a hybrid of phage and plasmid, which has the packaging and infection ability of phage, and also has the stability and operability of plasmid. Phagemid vector can be used to display smaller polypeptides or protein fragments.

According to the different types of libraries, phage display peptide library is divided into random peptide library, cDNA library, antibody library and protein library. Among them, random peptide library is a library containing a large number of random sequence polypeptides generated by chemical synthesis or gene synthesis, which is mainly used to screen polypeptides that bind to specific target molecules. The cDNA generated by reverse transcription of mRNA extracted from specific tissues or cells can be inserted into phage vector to construct cDNA library, which can be used to express and display corresponding protein or polypeptide fragments. The antibody library contains a large number of antibody gene sequences, which can be inserted into phage vectors and screened for antibodies against specific antigens through phage display technology. The protein library contains a large number of different protein or peptide sequences, which can be displayed on the surface of phages and used to screen proteins with specific functions or properties.

Tek Biotech is committed to providing customers with high-quality peptide library construction technology services, and providing strong support for customers' subsequent peptide library synthesis and screening, targeted peptide drug discovery, specific blocking peptide drug development, specific lead sequence development and other downstream research and development work. TekBiotech has rich project experience and insights in peptide library construction. After years of development, TekBiotech has established a complete peptide library construction system, including the M13 phage display system, M13 KE phage display system, T7 phage display system, etc., which rely on M13 helper phage. It can provide customers with high-quality linear peptide libraries (including but not limited to 6-peptide library, 7-peptide library, 12-peptide library, 15-peptide library) and cyclic peptide libraries (cyclic 6-peptide library, cyclic 7-peptide library, cyclic 10-peptide library, etc.) and other types of peptide library construction services. The M13 phage peptide library established by TekBiotech has a library capacity of up to 10^8 and a titer of up to 10^13 phage display peptide particles/ml. The T7 phage peptide library has a library capacity of up to 10^8 and a titer of up to 10^11 phage display peptide particles/ml, which is sufficient to support customers' subsequent screening of targeted peptides for various targets and meet downstream experimental needs. TekBiotech can provide one-stop technical services ranging from peptide gene library design and synthesis, peptide library construction to supporting peptide library screening, affinity verification, in vitro cell verification, etc. Customers only need to provide specific project requirements, and TekBiotech scientists will design the best library construction method and phage system according to the customer's project requirements to meet the customer's project needs.