Proteins naturally present in biological samples are immensely important to medical research ; their presence, absence, or misregulation can act as biomarkers of disease, diet, lifestyle, or genetics -for example, in diagnosis of cancers, bacterial identification, or assessment of therapeutic responseshowever, their relative size and complexity pose a challenge for unique identification by mass spectrometry. Two broad analytical approaches -colloquially, 'top-down' and 'bottom-up' proteomics -are commonly used to identify and quantify proteins in a sample. Top-down mass spectrometry-based proteomics aims to analyse native proteins whole, including both the parent mass and its constituent fragments, alongside any post-translational modifications . By contrast, bottom-up proteomics typically utilises chemical or enzymatic digestions (typically trypsin, but also elastase, pepsin, etc) to break bonds within the molecule, rendering smaller peptides available for MS analysis.