Top-down mass spectrometry of intact phosphorylated β-casein: Correlation between the precursor charge state and internal fragments.

ABSTRACT: Phosphorylated proteins play essential roles in many cellular processes, and identification and characterization of the relevant phosphoproteins can help to understand underlying mechanisms. Herein, we report a collision-induced dissociation top-down approach for characterizing phosphoproteins on a quadrupole time-of-flight mass spectrometer. β-casein, a protein with two major isoforms and five phosphorylatable serine residues, was used as a model. Peaks corresponding to intact β-casein ions with charged states up to 36⁺ were detected. Tandem mass spectrometry was performed on β-casein ions of different charge states (12⁺ , and 15⁺ to 28⁺ ) in order to determine the effects of charge state on dissociation of this protein. Most of the abundant fra

SUBMITTER: Chen J 

PROVIDER: S-EPMC6779312 | biostudies-literature | 2019 Jun

REPOSITORIES: biostudies-literature