Monoclonal antibodies are one of the most common types of biopharmaceuticals. Knowledge of an antibody’s molecular weight is essential; if this differs from predicted weight then this indicates that there is a change to the structure. One way of screening for these changes is through intact mass analysis by liquid chromatography-mass spectrometry (LC-MS). Although this is a useful screening technique, data still has to be interpreted with care. A case study will be used in this paper to highlight a few issues that need to be considered when interpreting this data.
IgG antibodies are large, complex macromolecules of around 150kDa comprised of two light and two heavy chains complexed via several disulphide bridges that have to be aligned correctly to ensure correct folding.