The Area Between Exchange Curves as a Measure of Conformational Differences in Hydrogen-Deuterium Exchange Mass Spectrometry Studies

Hydrogen-deuterium exchange mass spectrometry (HDX-MS) provides information about protein conformational mobility under native conditions. The area between exchange curves, A_bec, a functional data analysis concept, was adapted to the interpretation of HDX-MS data and provides a useful measure of exchange curve dissimilarity for tests of significance. Importantly, for most globular proteins under native conditions, A_bec values provide an estimate of the log ratio of exchange-competent fractions in the two states, and thus are related to differences in the free energy of microdomain unfolding. .