C7C Phage Display Peptide Library Screening Service

The phage display platform provided by KMD Bioscience is an ultra-high throughput ligand screening method. The phage display platform can construct up to 1013/ml peptides or antibody clones displayed on phage. After subsequent rounds of biopanning, KMD Bioscience can provide up to 105 validated peptide or antibody sequences, providing a solid research foundation for searches of subsequent enzyme substrate, protein ligand and high-specificity antibody. Based on the phage display platform, KMD Bioscience can build 7 peptide library, 12 peptide library and cyclic 7 peptide library, etc. for customers.

Cyclization modifications can confer several advantages to peptides that cumulatively make them more medicine-like. Constraining peptides via cyclization is a common strategy to mimic protein secondary structures (e.g. peptide rings) or to create peptides with enhanced conformational stability compared to their linear analogs. KMD Bioscience constructed a premade C7C phage display peptide library, aiming to construct a top-quality -peptide cyclization library.


Applications of Cyclic Phage Display Peptide Library:


Phage display of self-cycling peptides as an efficient and scalable approach to discover macrocyclic inhibitors of protein−protein interactions. 


Cyclic peptides are well suited for targeting protein−protein interactions. Due to their constrained structures, cyclic peptides benefit from lower entropic penalty upon binding and often show high affinity and specificity. They further display increased stability and cell permeability in comparison to linear peptides. Well-known natural product derived cyclic compounds such as cyclosporin A have inspired research in the field. Genetically encoded libraries of cyclic peptides are increasingly used to find cyclic compounds. Such libraries can be generated through a variety of approaches like phage display, mRNA display, and split-intein circular ligation. Bicyclic peptide phage libraries can further be generated by chemical cross-linking. Phage displays benefit from large library sizes and ease of experiments. Highly diverse cyclic M13 peptide-phage display libraries can be generated by designing randomized peptide sequences flanked by cysteine residues. However, the reversible nature of the disulfide bond limits the applicability of these cycles in an intracellular milieu.


Applications in enzyme inhibitors.


Cyclic peptides have been reported for the inhibition of proteases, phosphatases, proteasomes, HIV integrases, and dam methyltransferases. Cyclization peptides have been emphasized by academics in the area of inhibition of enzyme activity. Numerous groups have investigated the cyclization of peptides to enhance their inhibitory activity. As an example, the NS2b-NS3 protease of the Dengue virus is a serious viral infection transmitted by mosquito bites. There is no specific treatment available.NS2b-NS3 protease is a good antiviral target because it is required for viral maturation and infectivity.


Applications in RNA-protein interaction inhibitor.


RNA-protein binding processes can be interfered with by cyclic peptides. In laboratory studies, several groups have found that cyclic peptides can disrupt multiple processes of RNA-protein interactions, including: translation initiation, elongation, pre-mRNA splicing, and viral replication.


Construction of the C7C Phage Display Peptide Library:



Fig.1 Structure of the cyclic peptide

The C7C Phage Display Peptide Library is based on a combinatorial library of random peptides fused to a minor coat protein (pIII) of the M13 phage. The displayed peptide is expressed at the N-terminus of pIII, i.e., the first residue of the mature protein is the first randomized position. The peptide is followed by a short spacer (Gly-Gly-Gly-Ser) and then the wild-type pIII sequence.

Cyclization peptides more are resistant to proteolysis, increase the protein permeability, and can augment their affinities while preserving their selectivity. This is why cyclic peptides represent an increasingly interesting scaffold for studying and modulating protein−protein interactions.

Random oligonucleotide fragments of the cyclic 7-mer peptide were synthesized by chemical synthesis and then inserted into the gene encoding the shell protein of the phage vector and transformed into E. coli by genetic engineering recombinant technology. The proliferated and generated phages carry exogenous peptides on their surface, and each phage expresses one exogenous peptide on its surface. All these phages constitute a prefabricated cyclic 7 phage display peptide library.

Phage Display Peptide Library Screening:



The target molecule provided by the customer is used to obtain a monoclonal antibody that can bind to the target molecule with high affinity after a screening, amplification and selection step from the whole premade cyclic 7 phage display peptide library. By determining the DNA sequence of this phagemid, the amino acid sequence of the peptide carried by the phage can be known. The enriched cyclic peptides display a high affinity for the target protein and may serve as inhibitors of endogenous protein-protein interactions (PPIs).



Fig 2 Construction and screening of phage display cyclic peptide library.


C7C Phage Display Peptide Library Screening Service Process:


Services Available

Service Content

Service Time

Support Multiple Provision Forms

-Purified protein

-Unpurified protein (provides purification services)

-Targeted targets


Quality Control of Antigens

Antigen purity testing by SDS-PAGE

3 days

Peptide Library Screening

Positive clones recognizing antigen by 3-4 rounds of screening

2 weeks

Antibody Sequencing

Positive clone sequencing

1 week

Antibody Quality Control

Expression of target antibody in E.coli, followed by quality control by Elisa

1 week


Experimental report and

 >10 independent peptide clones

Depends on express


Advantage of Service:


-One-Stop Solutions for your research in immunology, proteomics and medicine discovery.

-Premade phage display peptide library constructed by KMD Bioscience for high throughput production.

-Accurate and fast experimental process, saving time for customers.

-Have professional technical experts to control the screening process accurately.

-Screening a large number of different clones without immunogenicity problems.

-Peptide screening is high specificity and high sensitivity.

-Widely used in the development of peptide medicines and accurate localization of antigenic determinants.

-Rapid production capability of soluble antigen: combined with our existing recombinant protein expression systems, we can produce high purity and high biological activity soluble antigens to support immunization or screening of target molecules.


How to Order?

If you have any questions regarding our services or products, please feel free to contact us by E-mail: info@kmdbioscience.com or Tel: +86-400-621-6806;