Characterization of the Primary Structure of Cysteine-Linked Antibody-Drug Conjugates Using Capillary Electrophoresis with Mass Spectrometry

Recent advances (2019-2021) of capillary electrophoresis-mass spectrometry for multilevel proteomics

Multilevel proteomics aims to delineate proteins at the peptide (bottom-up proteomics), proteoform (top-down proteomics), and protein complex (native proteomics) levels. Capillary electrophoresis-mass spectrometry (CE-MS) can achieve highly efficient separation and highly sensitive detection of complex mixtures of peptides, proteoforms, and even protein complexes because of its substantial technical progress. CE-MS has become a valuable alternative to the routinely used liquid chromatography-mass spectrometry for multilevel proteomics. This review summarizes the most recent (2019-2021) advances of CE-MS for multilevel proteomics regarding technological progress and biological applications. We also provide brief perspectives on CE-MS for multilevel proteomics at the end, highlighting some future directions and potential challenges.

Applications of capillary electrophoresis for biopharmaceutical product characterization

Capillary electrophoresis (CE), after being introduced several decades ago, has carved out a niche for itself in the field of analytical characterization of biopharmaceutical products. It does not only offer fast separation, high resolution in miniaturized format, but equally importantly represents an orthogonal separation mechanism to high-performance liquid chromatography. Therefore, it is not surprising that CE-based methods can be found in all major pharmacopoeias and are recommended for the analysis of biopharmaceutical products during process development, characterization, quality control, and release testing. Different separation formats of CE, such as capillary gel electrophoresis, capillary isoelectric focusing, and capillary zone electrophoresis are widely used for size and charge heterogeneity characterization as well as purity and stability testing of therapeutic proteins. Hyphenation of CE with MS is emerging as a promising bioanalytical tool to assess the primary structure of therapeutic proteins along with any impurities. In this review, we confer the latest developments in capillary electrophoresis, used for the characterization of critical quality attributes of biopharmaceutical products covering the past 6 years (2015-2021). Monoclonal antibodies, due to their significant share in the market, have been given prioritized coverage.

An online target and rapid screening method for α-glucosidase inhibitors based on capillary electrophoresis

Screening enzymatic active compounds is one of the important fields in drug research. α-Glucosidase can hydrolyze carbohydrates to monosaccharides after meals and lead to the rise of blood glucose levels in human body. Thus, the inhibition of α-glucosidase activity is an effective approach for the diabetes treatment. In this work, we developed a new method to simultaneously screen multiple bioactive compounds within a single CE running. The affect factors on the method performance, including injection, mixing, incubation, separation and detection, were carefully analyzed and discussed. Under the optimum, the mixture consisting of two internal standards (DMSO and 4-nitrophenol) and five compounds (lyoniresinol, hydroxytyrosol, rutin, kaempferol, and quercetin) was simultaneously screened, and kaempferol and quercetin showed stronger activity and this conclusion was also supported by offline assay. Furthermore, molecular docking was employed for investigating its interaction mechanism. Eventually, the established method has been applied to screen potential α-glucosidase inhibitors from an extract of Lycium barbarum and the peak area of rutin, taxifolin, quercetin, and chlorogenic acid in L. barbarum samples changed before and after the enzymatic reaction, confirming that these four compounds had potential inhibitory activities, which was consistent with the literature data. The present work provides a promising method for the target and rapid discovery of bioactive compounds from a plant extract or mixture.