Alpha Lifetech Inc. has developed a T7 phage display technology, by which we can offer a convenient tool for peptide library construction and screening.

Phage Display Library – T7 Phage Library Construction Service

In contrast to the common forms of M13, in which the presented peptides of interest are affixed through their carboxyl terminus, T7 phage peptides are anchored to viral coat proteins through their amino ends (N-terminus). Bacteriophage T7 is a lytic phage, replicating and amplifying within the host cells, and phage progeny is released by host cell lysis. The mature T7 virion contains 40-kbp genomic DNA which encodes approximately 55 types of proteins including capsid protein 10B. Protein gp10B, as a fusion, displays the C-termini of the random peptide repertoire at the surface when an engineered degenerate oligonucleotide is inserted at capsid protein 10B gene, thereby making it suitable for use in the development of ligands for some domain families. Unlike the filamentous systems, T7-displayed peptides or proteins do not require secretion through the bacterial cell membrane, and thus are not as biologically constrained as the M13 phage display system. The lytic feature of T7 phage also shortens the time separating one round of biopanning selection from the next. Further, peptide libraries based on phage T7 are reported to exhibit fewer amino acid biases and increased peptide diversity over M13 libraries in some cases.

Anyway, the T7 phage display system is suitable for high-copy display of peptides or proteins with small molecule weight (50 amino residues or shorter). We have created a strong promoter and translation initiation control element to regulate the expression of capsid gene of T7 phage. As a result, a large amount of capsid/fusion protein is produced during infection, leading to the display of 415 copies of peptide on the surface of the phage. The high copy number of T7 fusions promotes avidity and helps in the recovery of even weak binders of the target protein. The presence of a strong promoter and controller ensures rapid growth in the host E. coli BL21 cells without any host cell modification.

Service Features of T7 Phage Library Construction Service

-- High throughput analysis of protein interactions

-- Excellent diversity: 10⁸ - 10¹²

-- Display size: <132 kD

-- Display density: up to 415 copies for each T7 particle

-- Excellent for peptide library construction with free C-terminus 

Ror more information, please feel free to contact us at any time.