The protons present on protein amides and backbone are labile by nature. When dissolved in solution proteins routinely exchange these protons with hydrogen groups in the solution. Hydrogen deuterium exchange mass spectrometry (HDX-MS) takes advantage of this phenomena by exchanging the protons from the protein with deuterium in deuterated solutions. The rate of hydrogen-to-deuterium exchange provides solvent accessibility information which can be used to infer protein structure and conformation. For single protein and protein complexes, HDX can be used to obtain protein structure and conformation information. Additionally, for protein complexes HDX can provide information on protein-protein or protein-ligand interaction sites and conformational changes induced by posttranslational modifications (PTMs