Estimation of Rates of Reactions Triggered by Electron Transfer in Top-Down Mass Spectrometry

Abstract

Electron transfer dissociation (ETD) is a versatile technique used in mass spectrometry for the high-throughput characterization of proteins. It consists of several competing reactions triggered by the transfer of an electron from its anion source to the sample cations. One can retrieve relative quantities of the products from mass spectra. We present a method to analyze these results from the perspective of the reaction kinetics. A formal mathematical model of the ETD process is introduced and parametrized by intensities of the occurring reactions. Also, we introduce a method to estimate the reaction intensities by solving a nonlinear optimization problem. The presented method proves highly robust to noise on in silico generated data. Moreover, the presented model can explain a considerable amount of experimental results obtained under various experimental settings.