A molecule of water (H2O) consists of two hydrogen (H) atoms and one atom of oxygen (O). Hydrogens are also more or less equally distributed throughout a protein. Some of these hydrogens, such as backbone amide hydrogens, engage in exchange with solvent hydrogens on time frames amenable to analysis. Upon transfer from an H2O based solvent system to one primarily consisting of D2O, a form of water containing the heavier isotope of hydrogen (deuterium or D), exchange of H for D atoms over time result in an increase in protein mass. The likelihood that a particular amide will undergo exchange is largely a function of protein structure and solvent accessibility. Molecular motions present in all protein, collectively referred to as protein dynamics, facilitate solvent accessibility by momentarily changing or disrupting protein structure. ExSAR follows hydrogen/deuterium exchange by mass spectrometry (HXMS). Using the shift in protein mass as a marker, we can analyze how protein targets respond to the drugs that bind them.



H/D Exchange Overview | H/D Exchange Science | H/D Exchange Applications | H/D Exchange Partnering Opportunities