Effects of temperature and relative humidity in D2O on solid-state hydrogen deuterium exchange mass spectrometry (ssHDX-MS)

Abstract

Lyophilized powders containing myoglobin and various excipients were subjected to ssHDX-MS at different temperatures and D2O vapor activity (RH). Deuterium incorporation was fitted to a bi-exponential association model for each formulation and the dependence of regression parameters on temperature and RH was evaluated. Data fitted best to a simplified model in which the slow exponential term was considered invariant with temperature and RH while the fast exponential term retained its temperature and RH dependence. This suggests that rapid rate processes such as water vapor sorption and initial deuterium labeling may be more dependent on temperature and RH than slower processes such as sequential exchange and transport in the solid matrix.