Utilizing ion mobility to identify isobaric post-translational modifications: resolving acrolein and propionyl lysine adducts by TIMS mass spectrometry
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Protein post-translational modifications provide critical proteomic details towards elucidating mechanisms of altered protein function due to toxic exposure, altered metabolism, or disease pathogenesis. Lysine propionylation is a recently described modification that occurs due to metabolic alterations in propionyl-CoA metabolism and sirtuin depropionylase activity. Acrolein is a toxic aldehyde generated through exogenous and endogenous pathways, such as industrial exposure, cigarette smoke inhalation, and non-enzymatic lipid peroxidation. Importantly, lysine modifications arising from propionylation and acroleination can be isobaric – indistinguishable by mass spectrometry – and inseparable via reverse-phase chromatography. Here, we present the novel application of trapped ion mobility spectrometry (TIMS) to resolve such competing isobaric lysine modifications. Specifically, the PTM products of a small synthetic peptide were analyzed using a prototype TIMS – time-of-flight mass spectrometer (TIMS-TOF). In that the mobilities of these propionylated and acroleinated peptides differ by only 1%, a high-resolution mobility analysis is required to resolve the two. We were able to achieve more than sufficient resolution in the TIMS analyzer (~170), readily separating these isobars.
KeywordsAcylation Propionylation Propionyl-CoA Acrolein Oxidative stress Mass spectrometry Ion mobility shift
The authors wish to thank Joshua Silveira for technical support and thoughtful discussion. Molecular modeling was performed in collaboration with Dr. Don Backos in Computational Chemistry and Biology Core Facility (NIH/NCATS CCTSI UL1TR001082). Studies were supported, in part, by 1R01AA022146-04 (KSF).
Conceived and designed the experiments: JDG, KSF.
Performed the experiments: MAP, MER, KSF. Analyzed the data: JDG, MER, MAP, KSF. Contributed reagents/materials/analysis tools and wrote the manuscript: JDG, MER, MAP, KSF.
All authors have given approval to the final version of the manuscript.
Compliance with ethical standards
The authors declare no competing financial interests.
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