title: Improving data quality and preserving HCD-generated reporter ions with EThcD for isobaric tag-based quantitative proteomics and proteome-wide PTM studies.
abstract: Mass spectrometry (MS)-based isobaric labeling has undergone rapid development in recent years due to its capability for high throughput quantitation. Apart from its originally designed use with collision-induced dissociation (CID) and higher-energy collisional dissociation (HCD), isobaric tagging technique could also work with electron-transfer dissociation (ETD), which provides complementarity to CID and is preferred in sequencing peptides with post-translational modifications (PTMs). However, ETD suffers from long reaction time, reduced duty cycle and bias against peptides with lower charge states. In addition, common fragmentation mechanism in ETD results in altered reporter ion production, decreased multiplexing capability, and even loss of quantitation capability for some of the isobaric tags, including custom-designed dimethyl leucine (DiLeu) tags. Here, we demonstrate a novel electron-transfer/higher-energy collision dissociation (EThcD) approach that preserves original reporter ion channels, mitigates bias against lower charge states, improves sensitivity, and significantly improves data quality for quantitative proteomics and proteome-wide PTM studies. Systematic optimization was performed to achieve a balance between data quality and sensitivity. We provide direct comparison of EThcD with ETD and HCD for DiLeu- and TMT-labeled HEK cell lysate and IMAC enriched phosphopeptides. Results demonstrate improved data quality and phosphorylation localization accuracy while preserving sufficient reporter ion production. Biological studies were performed to investigate phosphorylation changes in a mouse vascular smooth muscle cell line treated with four different conditions. Overall, EThcD exhibits superior performance compared to conventional ETD and offers distinct advantages compared to HCD in isobaric labeling based quantitative proteomics and quantitative PTM studies.
authors.affiliation: School of Pharmacy, University of Wisconsin, Madison, WI 53705, USA.
authors.forename: Qing
authors.initials: Q
authors.lastname: Yu
authors.affiliation: Department of Surgery, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53705, USA.
authors.forename: Xudong
authors.initials: X
authors.lastname: Shi
authors.affiliation: School of Pharmacy, University of Wisconsin, Madison, WI 53705, USA.
authors.forename: Yu
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Department of Surgery, School of Medicine and Public Health, University of Wisconsin, Madison, WI 53705, USA.
authors.forename: K Craig
authors.initials: KC
authors.lastname: Kent
authors.affiliation: School of Pharmacy, University of Wisconsin, Madison, WI 53705, USA; Department of Chemistry, University of Wisconsin, Madison, WI 53706, USA. Electronic address: lingjun.li@wisc.edu.
authors.forename: Lingjun
authors.initials: L
authors.lastname: Li
mesh_terms: D000818:Animals; D002460:Cell Line; D000068598:Data Accuracy; D007477:Ions; D013058:Mass Spectrometry; D051379:Mice; D032389:Myocytes, Smooth Muscle; D011499:Protein Processing, Post-Translational; D020543:Proteome; D040901:Proteomics
chemical_list: D007477:Ions; D020543:Proteome
keywords: DiLeu; EThcD; Isobaric tag; Post-translational modification; Quantitative proteomics; TMT