Phage display 12 peptide Library Construction Service

Alpha Lifetech offer a range of phage display peptide library construction services such as M13, T4, T7 or λ phages for our customers, with M13 phage display being our commonly used method. We are capable of constructing linear peptide libraries and structurally stable cyclic peptide libraries. We can tailor peptide libraries with different structures containing 5-25 amino acids. In addition to linear 7-mer peptide libraries, we also construct cyclic 7-mer peptide libraries, linear 12-mer peptide libraries, linear 15-mer peptide libraries, linear 9-mer peptide libraries and cyclic 9-mer peptide libraries.

Introduction to Peptide Phage Display

Phage display is an in vitro screening technique that uses the phage as a carrier to display a library of peptides or proteins on the outside of the phage particle, while the DNA encoding these proteins is located inside the virus particle. This technique allows us to quickly screen for ligands with affinity to a given target molecule, such as antibodies, enzymes, cell surface receptors, etc., through a simple in vitro screening method known as "biopanning."

Peptide phage display technique allows high affinity target-binding peptides to be selected from a complex mixture pool of billions of displayed peptides on phage in a combinatorial library and could be further enriched through the biopanning process; proving to be a powerful technique in the peptide phage display screening with high affinity and selectivity. \

In the display of peptide phages, the commonly used phages are mainly the following: E. coli filamentous phage M13, T4 phage, T7 phage, λphage.

Fig.1 A typical representation of M13 phage ( Reference source: Advance in phage display technology for bioanalysis.)

Phage Library Construction Key Elements of Dodecapeptide

Phage Carrier Selection

Choosing the right phage carrier is critical to ensure the correct expression and display of the polypeptide.

E. Coli Expression System

The expression system of E. coli should be stable and efficient to support phage growth and peptide expression.

Optimization Of Screening Method

Optimization of biological panning method can improve screening efficiency and purity of affinity ligand.

Quality Control

Quality control of the constructed peptide library, including the detection of concentration, number of specific sequences and other indicators, to ensure the quality and reliability of the peptide library.

Peptide Library Screening Process

Phage display library construction

Building a library containing a large number of phages of different sequences that display a wide variety of foreign peptides or proteins on their surface. This library can be achieved by genetically engineering fragments of foreign DNA into the phage coat protein structural gene.

Affinity screening

Affinity screening of phage display libraries using specific target molecules (e.g. antigens, antibodies, receptors, etc.). During phage display screening, target molecules selectively bind to foreign peptides or proteins on the surface of certain phages.

Elution and amplification

Through elution steps, phages that are not bound to target molecules can be removed. Then, the phage bound to the target molecule infects the host cell and is amplified to get more phage clones.

Multiple rounds of screening: In order to improve the specificity and affinity of phage display screening, multiple rounds of screening are usually required. In each round of screening, the same target molecules are used, but the rigor of the screening may be gradually increased (such as reducing the concentration of the target molecules, increasing the screening time, etc.).

Sequence analysis and cloning

Finally, sequence analysis is performed on phage display screened to determine the sequence of foreign peptides or proteins displayed. These phages can then be selectively cloned for further research or applications.

Fig.2 The general scheme of phage display technique and biopanning selection of high affinity peptide. (Reference source: phage display screening of therapeutic peptide for cancer targeting and therapy.)

Phage Display Peptide Library Construction Workflow

Process	Service Content	Timeline
1. Design of Peptide Library	Peptide libraries are designed with specific sequences, usually containing a large number of random sequences, to ensure that as many amino acid combinations as possible can be covered.	1 day
2. Synthetic Genes Encoding Random Peptide Segments	Using chemical synthesis or genetic engineering techniques to artificially synthesize genes encoding random dodecapeptide segments.	1 week
3. Cloning A Gene Into A Phage Vector	The synthetic gene is cloned into a phage vector, usually the N terminal of the secondary coat protein (pIII) of the M13 phage.	1 day
4. Expression and Display	The phage vector is expressed in Escherichia coli (E. coli K12 ER2738), so that the polypeptide is fused with the phage coat protein and displayed on the phage surface.	1 week