Peptide Modification for Fundamental Research

Peptide modifications play a vital role in basic research. This technology not only helps researchers to deeply explore the structure-function relationship of peptides, but also provides powerful tools and methods in fields such as biomedicine, chemistry, and biotechnology. In this article, we elaborate on the multiple applications of peptide modifications in basic research, including important areas such as click chemistry and binding to carrier proteins to induce immune responses. The application of click chemistry makes the synthesis and labeling of peptide molecules more efficient and precise, which is helpful for studying their behavior and function in biological systems. By binding peptides to carrier proteins, a strong immune response can be induced, which is important in vaccine development and immune research. By continuously optimizing and innovating these technologies, we are able to better understand the complexity of life processes and advance science in all related fields.

Table 1. Peptide modification service at Creative Peptides

Self-assembly after peptide modification

Self-assembled peptides have attracted extensive attention due to their application potential in biomedical imaging, drug delivery, and disease diagnosis, and have become one of the frontier fields of research in recent years. The self-assembly process of biomolecules such as proteins and peptides is widely present in the physiological activities of organisms in nature, and its assemblies have good biocompatibility and controllable assembly functions in organisms, which can achieve aggregation and retention in the lesion area. The driving forces of peptide self-assembly mainly include π-π stacking, electrostatic interaction, hydrogen bonding, and hydrophobic, which enable peptide assembly to form specific nanostructures. The secondary structure of peptides in assemblies is usually β-lamellar and α-helix and the morphology of assemblies is diverse and their uses are also different. Self-assembled peptides have an assembly-induced retention effect (AIR), that is, peptides are assembled in organisms due to endogenous factors, which can stay in the lesion area for a long time, enhance aggregation and effect, and reduce toxicity to normal tissues.

In order to meet the needs of drug delivery and disease diagnosis and treatment, peptides need to be functionalized. The modification sites mainly include amino and carboxyl groups in the main chain, as well as amino, carboxy, hydroxyl, and sulfhydryl groups in the side chains. The modification of functional molecules can be carried out in a direct or indirect way, including drug molecules, probe molecules, alkyl chains, polymers, sugars, etc., and indirect modification uses linker units to link functional molecules with peptides. The modified self-assembled peptide has greater advantages in assembly capacity and biomedical application and is an effective strategy to solve the problem of poor recognition and enrichment ability of small molecule drugs in the lesion area, easy degradation in the internal circulation, and large toxic side effects on normal cells and tissues.

Fig.1 Direct and indirect modification of peptides. (Ren Han, et al., 2021)

Peptide modification in click chemistry

Click chemistry is a highly efficient, selective, and mild chemical reaction that is widely used in chemical synthesis and biomolecular labeling. The combination of peptide modification and click chemistry can achieve efficient linkage of peptides with other molecules, thereby expanding the functions and application range of peptides. In click chemistry, a common approach is to combine a peptide with 5-azidovalonic acid and then react with an alkyne in the presence of Cu/CuSO₄ to form triazole. For example, this method can be used to combine peptides with alkyne-modified DNA oligonucleotides to generate multi-functional heterozygous molecules. This technique can be used not only to study peptide-DNA interactions, but also to develop new biosensors and diagnostic tools. In addition, the azide group can also bind to the lysine side-chain primary amino group in the peptide, thus achieving specific modification of the peptide. This approach has important applications in the development of biomolecular labeling and drug discovery. For example, the combination of bioactive peptides with fluorescent molecules can be used to monitor the distribution and dynamics of peptides within cells in real-time, thus providing new perspectives for biomedical research.

Fig.2 Types of click chemistry applications in peptide-based drug discovery. (Li Huiyuan, et al., 2013)

Table 2. Peptide conjugation service at Creative Peptides

Binds to carrier proteins to induce immune responses

In immunology research, peptide-carrier protein modification is a common means to prepare specific antibodies. Since individual peptide molecules are usually small, it is difficult to elicit a strong immune response, while carrier proteins (e.g., KLH, BSA, OVA) have multiple epitopes that can effectively stimulate helper T cells, thereby enhancing the immune response of B cells. For example, the conjugation of antigenic peptides to KLH (pangolin hemocyanin) allows for the preparation of highly effective peptide antibodies. These antibodies are not only used in basic research to study protein function, but are also widely used in disease diagnosis and treatment. In addition, BSA (bovine serum albumin) and OVA (ovalbumin) are also commonly used in peptide modifications to prepare peptide antibodies. These antibodies can play an important role in techniques such as enzyme-linked immunosorbent assay (ELISA), immunofluorescence, and flow cytometry.

Summary

Peptide modification has a wide range of applications in basic research, which has greatly promoted the functional research of peptides and their derivatives and has had a profound impact in the fields of biomedicine, chemistry, and biotechnology. These technologies not only help scientists gain insight into the structure and function of biomolecules, but also advance the development of novel drugs and therapeutics. For example, through chemical modification, the stability and biological activity of peptides can be improved, and their effects in vivo can be enhanced. In addition, peptide modifications also show great potential for the development of diagnostic tools and sensors. As these technologies continue to evolve and be optimized, we are able to manipulate peptide properties more precisely, uncover key mechanisms in life processes, and make important contributions to human health and scientific progress.

References

1. Ren, Han, et al., Modification Methods and Applications of Self-Assembly Peptides. Chinese Journal of Organic Chemistry (2021): 10.
2. Li, Huiyuan, et al., Click chemistry in peptide-based drug design. Molecules 18.8 (2013): 9797-9817.
3. Katayama, Hidekazu, et al., A novel approach for preparing disulfide-rich peptide-KLH conjugate applicable to the antibody production. Bioscience, Biotechnology, and Biochemistry 83.10 (2019): 1791-1799.