Mass spectrometry (MS)

Mass spectrometry (MS) is an analytical tool that determines the precise mass of molecules. The measured value is the ratio of mass over charge of synthetic ions. These ions are generated inside the mass spectrometer from the sample. This may be used to identify a molecule after a separation process as liquid chromatography (LC) for example. Moreover, information about configuration may be found thanks to macromolecules fragmentation. In protein studies, the peptidic chain is cut into smaller ions whose nature depends on the bond that was cleaved and the atom receiving the charge coming from the cleavage. Tandem mass spectrometry (MS/MS) fragments further the former ions to give son ions whose masses can be accurately measured. This technique has been applied in proteomics to sequence proteins. It also provides information on modifiers or other conjugated molecules that the protein may carry.

Mass spectrometry may thus be applied to antibodies. In addition to sequencing, it allows to know the post translational modifications such as glycosylations which are critical quality attributes for the antibodies’ characterization. The oxidation level and subunit characterization can be analyzed as well. It may also be used in antibody drug conjugates (ADC) development to control the conjugation of the additional molecules. These data may be important as they impact the affinity, stability, or aggregation of antibodies. They are critical parameters in the development of therapeutic or diagnostic antibodies for example. To achieve these analysis different pathways may be chosen depending on the needed accuracy and time availability. Top-down strategy is the study of the intact mass whereas bottom-up is the fragmentation at the peptide level. A middle technique can be used also to separate the subunits and the glycans.

ProteoGenix offers a range of stable isotope labeled antibodies. These tools will prove useful as internal standards for MS identification and quantification.