Since the invention of monoclonal antibody preparation technology in the 1970s, it has been rapidly applied to the field of clinical diagnosis and treatment, greatly promoting the development of medicine. The emergence and development of monoclonal antibody have brought new challenges to drug analysis. The drug standards are directly related to the quality of the drug. It is a measure to control drug safety, effectiveness and quality reliability from the source. With the development of biotechnology drugs, the safety of biological products has also attracted more attention. Since monoclonal antibodies may contain harmful substances that are not present in traditional production methods, the quality control of monoclonal antibody is fundamentally different from those produced by traditional methods, and the quality control is more complicated and diverse. Beside identifying the final products, it is also necessary to strictly control each production step, such as cultivation and purification to ensure the effectiveness, safety and consistency of the final product.
Recombinant monoclonal antibodies are one of the great achievements of modern biotechnology. There is no doubt that the uses of them are successful in treating various life-threatening and chronic diseases including cancer, autoimmunity, transplantation and infectious ones. Its share in the global bio-pharmaceutical market has also increased rapidly in recent years. Meanwhile, as one of the most successful bio-therapeutics, how to ensure the safety and efficacy of recombinant antibody products through well-established quality control system is always the focus of attention from both the views of regulatory authorities and industries. This article briefly introduce the research contents and techniques for the control of recombinant antibodies.
Physical and chemical analysis
Structure confirmation
Structure confirmation mainly include N-terminal amino acid sequence, peptide map, glycosylation analysis, etc. Terminal amino acid sequencing is one of the ways to identify the primary structure of antibody. N- terminal amino acid determination is most commonly used by Edman degradation.To further identify the primary structure of the recombinant antibody, liquid peptide map or peptide mass fingerprint analysis can be performed. Glycosylation and protein modifications are important not only for drug stability and efficacy, but also they may have consequences for the patient. For example, incorrect modifications, including aggregation may lead to an immune response to the therapeutic monoclonal antibody. At present, the sugar chain structure can be predicted by measuring the relative molecular mass of the sugar chain in combination with the existing literature, it can also be determined by tandem mass spectrometry.
Purity analysis
The purity of the antibody drug directly reflects the level of the purification process and the quality of the product. In order to avoid the deviation of a detection method in protein purity detection, two different principles are generally used at least for detection to separate impurities as much as possible and obtaining relatively accurate results. Common methods include SDS-PAGE, capillary electrophoresis, and high performance liquid chromatography such as reverse phase, molecular exclusion and ion exchange.
Protein content determination
The commonly used methods for protein content determination include spectrophotometry, Lowry method, Bradford method, BCA method, Kjeldahl method. At present, most of the recombinant antibodies are measured by spectrophotometry.
Other physical and chemical characteristics analysis
It mainly includes relative molecular mass and isoelectric point. The measurement is carried out by SDS-PAGE and isoelectric focusing electrophoresis respectively.
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