Analysis of Isotopic Peaks in Hydrogen/Deuterium Exchange Mass Spectra for Precise Measurement of Isotope Average Centroid Mass of Peptides and Proteins Using R Programming Language

In hydrogen/deuterium exchange mass spectra, the shift in isotopically distributed peaks with deuterium incorporation into peptides results in an increase in the isotope average centroid mass. Due to limitations in the resolution of instruments and data processing by softwares, the observed peaks might have obscurity in its maxima values that can affect the centroid mass calculation. In the present study, using Gaussian function, the exact maxima of individual isotopic peaks of a distribution was calculated. Using those maxima and our customized program, the centroid mass was calculated. We propose that our method of calculating average centroid mass is mathematically more appropriate.