Recommendations for the Propagation of Uncertainty in Hydrogen Exchange-Mass Spectrometric Measurements

Hydrogen exchange-mass
spectrometry (HX-MS) is used widely to characterize
higher-order protein structure and to locate changes in protein structure
and dynamics that accompany, for example, ligand binding and protein–protein
interactions. Quantitative differences in the amount of hydrogen exchange
between two states (i.e., differential HX) are taken as evidence of
significant differences in higher-order structure or dynamics. The
quantitative measures range from simple mass differences at one HX
labeling time to differences averaged across an HX time course with
correction for deuterium recovery. This work applies the principles
of uncertainty propagation to differential HX measurements to facilitate
the identification of significant differences. Furthermore, it is
shown that pooled estimates of experimental uncertainty result in
a lower false positive rate than estimates of uncertainty based on
individual standard deviations.