MEASUREMENT OF PROTEIN MOLECULAR FLUX RATES BY QUANTIFYING ISOTOPOLOGUE ABUNDANCES IN IMMONIUM ION FRAGMENTS USING HIGH RESOLUTION MASS SPECTROMETRY

摘要

Provided herein are methods for measuring a molecular flux rate proteins and polypeptides based on analysis of isotopologue abundances of immonium ion fragments within a mass isotopomer using a high resolution mass spectrometric measurement. Such methods may be used, inter alia, to calculate a fraction of newly synthesized protein or polypeptide molecules of interest, a replacement rate of target molecules of interest, and/or a rate of breakdown or degradation of target molecules of interest, e.g., based on isotopologue relative abundances.