Protein Post-Translational Modification
Post-translational modification (PTM) plays a critical role in the processing and maturation of proteins. It can alter the physical and chemical properties of proteins, affecting their spatial conformation, steric hindrance, and stability. These changes can also impact the biological activity of the protein, leading to a modification of its function. Post-translational modified proteomics enables the identification of molecular regulation mechanisms in life activities, biomarker screening, and drug target identification.
Post-Translational Modification of Protein Drugs
Regulatory enzymes responsible for PTM of proteins have become a frontier and hot target in the field of new drug research. The integrity of protein drugs requires specific biological activities and functions produced after a series of protein PTM processes, in addition to the complete amino acid sequence. The modification and processing methods of protein drugs have diverse characteristics, including but not limited to glycosylation, phosphorylation, ubiquitination, acetylation, methylation, and others. Therefore, PTM analysis of protein drugs is crucial in their development and production. Naturally modified protein drugs have an essential role in determining their modification type, modification site, and modification structure to improve their modification or processing efficiency. This information can be used to improve the production process in the research and development or production process of biopharmaceutical companies, ultimately improving the efficiency of biopharmaceutical development.
- Core histone post-translational modification
Post-translational modification of core histones is currently the most studied direction in drug research and development. Histone modification mainly includes acetylation, methylation, phosphorylation, ubiquitination, and others. These modifications can recruit recognition proteins that recognize the modification site, and then recruit other transcription factors or form complexes with many physiological functions, carrying out transcriptional regulation. Therefore, researchers have defined their image as “Writer,” “Eraser,” and “Reader,” according to the mechanism of action of different regulatory factors. Write factors add modified enzymes to DNA or proteins, including methylation, acetylation, glycosylation, ubiquitination, phosphorylation, and oxidation (for proteins). The erasing factor removes the acetyl group on the histone lysine residue, changing the charge and making the chromatin structure compact, inhibiting the transcriptional expression of the gene. Recognition factors can recognize these modified proteins and recruit other transcription factors or proteins to regulate physiological functions in the body.
- Glycosylation of antibody drugs
Among the many PTMs of proteins, glycosylation modification is one of the most important and complex modifications and a key quality attribute for evaluating antibodies. The realization of monoclonal antibody drug function is closely related to its glycosylation modification, which affects the performance of the protein, such as conformation, stability, solubility, pharmacokinetics, activity, and immunogenicity. Protein glycosylation modification can increase the stability and solubility of proteins. Different glycosylation modifications have different effects on the stability, half-life, safety, and biological activity of antibodies. For example, studies have shown that glycosylation can protect proteins by hiding their binding sites with proteases, and it can also hinder the binding of proteases to antibodies, thereby increasing the stability of antibodies.
Analysis Method of Protein Post-translational Modification
- Mass spectrometry
Mass spectrometry is an important method for identifying PTMs of proteins. Its principle is to use the mass shift of modified proteins to identify PTM sites. Biopharmaceutical products may contain a variety of variants or derivatives derived from functional PTMs or modifications, such as glycosylated variants (mAb) or ADCs. Therefore, we need a suitable technique for characterizing and quantifying substances with the above-mentioned complexity. Liquid chromatography-mass spectrometry (LC-MS) is a mature biopharmaceutical characterization technique because it can directly perform qualitative and quantitative determination at the molecular level. The application of this technology in other fields is also becoming more and more extensive, including macromolecular drug metabolism and pharmacokinetics (DMPK) research, process development, production, quality control, post-market supervision, and therapeutic drug monitoring.
- PTMScan®
PTMScan® is a proteomics technology specifically used for protein PTM research. It utilizes antibodies against protein PTM motifs to immunoaffinity enrich peptides with different PTM at the peptide level Peptides are quantified using liquid chromatography-tandem mass spectrometry (LC-MS / MS), enabling fast, accurate, and high-throughput analysis of key node protein phosphorylation, acetylation, methylation, and the changes of ubiquitination modification meet the needs of innovative research, biomarker identification, drug target screening and evaluation. PTMScan technology can identify new protein modification sites and open up new directions for protein function research, so it will be an important branch and trend of next-generation proteomics research.
