Frontiers in Targeted Drug Development: Comparison and Application of Various Peptide Screening Methods-Special Topic on Phage Display Technology-Tekbiotech-Yeast and Phage Display CRO, Expert in Nano-body and Antibody Drug Development

Frontiers in Targeted Drug Development: Comparison and Application of Various Peptide Screening Methods

A target peptide is a short amino acid sequence (typically composed of 5–15 amino acids) that can bind to specific targets with high affinity and specificity.

Compared to conventional antibodies, peptide molecules are smaller in size and exhibit enhanced ability to penetrate tissue barriers (such as tumor tissues); they are less likely to trigger immune responses in humans, thereby offering higher safety profiles; and they are more amenable to various chemical modifications. Consequently, identifying the "right" peptide is of paramount importance. This article primarily describes several characterization techniques and methodologies.

1．Classic Technology – Phage Display Technology

The core principle of phage display involves fusing the gene encoding an external peptide or protein with the capsid protein gene. During phage assembly, the external peptide is displayed on the phage surface, while the corresponding gene remains within the phage, thereby establishing a precise linkage between phenotype and genotype, providing a foundation for subsequent genetic modifications.

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Figure 1: The M13 filamentous bacteriophage pVIII displays the OVA molecule ^[3]

Filter Process:

Standard protocol – Biological screening: Based on the affinity between the immobilized target molecule and the peptide library, phages capable of binding to the target molecule are enriched through multiple cycles of "binding-elution-amplification".

Tek Biotechnology employs blue-white and white-spot screening methods for library construction. First, gene libraries are synthesized using Trimer codon technology, NNK technology, or error-prone PCR technology, with foreign genes specifically inserted into the N-terminus of the wild-type M13 phage P3 protein to maximize their infectivity. Next, the constructed phage library is incubated with "functional" targets (e.g., enzymes), which infect bacteria and are cultured on plates containing specific substrates or indicators. If the target enzyme can be bound to or inhibited by the displayed peptide, its activity will be suppressed, allowing bacterial growth and formation of visible clones (spots). Conversely, if the target enzyme cannot be bound or inhibited, it remains active, leading to bacterial death or failure to produce color changes (forming "blue spots" or "white spots," depending on the design). Finally, surviving clones are selected for sequencing.

Traditional phage-based biological screening techniques offer large library capacities and mature methodologies. However, the processes are time-consuming and limited by bacterial transformation efficiency, making it difficult to introduce non-natural amino acids for identifying novel candidate peptides. The wild-type M13 display technology described by Thermo Scientific is particularly suitable for one-step phenotypic screening of enzyme targets (especially those whose activity can be translated into phenotypic changes). This approach features a relatively straightforward procedure, high infection efficiency, and potentially lower false-positive rates due to direct functional readout.

2．mRNA display technology

The essence of mRNA display is a platform for "directed evolution" implemented in vitro, completely free from the limitations of cell transformation efficiency. It locks the functional properties (phenotype) of proteins to their encoding genes (genotype) through purine-mediated covalent linkage, enabling the efficient selection of protein molecules with desired functions from vast populations of random sequences via multiple rounds of "screening-amplification" cycles.

Figure 2 Formation of mRNA-protein fusion on the ribosome [1]

The procedure is similar to that of classical phage display: the mRNA-peptide complex library is incubated with the target, unbound complexes are washed away, and the corresponding mRNA gene encoding the target-bound peptide is then recovered and amplified using techniques such as reverse transcription PCR for subsequent screening or sequencing analysis.

Figure 3: Complete workflow of mRNA display technology [2]

3．Peptide Chip Technology

This technique employs microarray technology to densely immobilize hundreds or even thousands of peptides with known sequences on a solid-phase support (e.g., glass slides). Subsequently, fluorescently labeled target proteins are applied across the chip surface, and the binding affinity of these peptides to the target is rapidly determined based on fluorescence signal intensity. It is primarily utilized for candidate peptide validation, affinity comparison, epitope mapping (to identify antibody-binding regions), and related applications.

Tek Biotechnology (Tianjin) Co., Ltd. specializes in phage display and yeast display antibody development services as its core business, positioning itself as a high-tech enterprise at the forefront of biopharmaceuticals dedicated to providing clients with advanced "one-stop targeted peptide discovery and optimization" solutions. Our services cover all critical stages of early drug discovery: novel targeted peptide identification, lead peptide optimization, and customized screening strategies, tailored to specific client requirements to address complex biological challenges.

References

[1] Liu R,Barrick JE,Szostak JW, et al. Optimized synthesis of RNA-protein fusions for in vitro protein selection. Methods Enzymol. 2000;318:268-93.

[2] Hammond PW,Alpin J,Rise CE, et al. In vitro selection and characterization of Bcl-X(L)-binding proteins from a mix of tissue-specific mRNA display libraries. J Biol Chem. 2001;276 (24):20898-906.

[3] Hess KL, Jewell CM. Phage display as a tool for vaccine and immunotherapy development. Bioeng Transl Med. 2019 Sep 18;5(1):e10142.

[4] Schmitz U, Versmold A, Kaufmann P, Frank HG. Phage display: a molecular tool for the generation of antibodies--a review. Placenta. 2000;21 Suppl A:S106-S112.

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