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Updated: Jun 11, 2026

Profiling Thiol Redox Proteome Using Isotope Tagging Mass Spectrometry
Published on: March 24, 2012
Identification of disulfide bonds in protein proteolytic degradation products using de novo-protein unique sequence
Yufeng Shen1, Nikola Tolić, Samuel O Purvine
1Biological Sciences Division, and Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99354, USA. Yufeng.shen@pnl.gov
Abstract:
Disulfide bonds are a form of post-translational modification that often determines protein structure(s) and function(s). In this work, we report a mass spectrometry method for identification of disulfides in degradation products of proteins, specifically endogenous peptides in the human blood plasma peptidome. LC-Fourier transform tandem mass spectrometry (FT MS/MS) was used for acquiring mass spectra that were de novo sequenced and then searched against the IPI human protein database. Through the use of unique sequence tags (UStags), we unambiguously correlated the spectra to specific database proteins. Examination of the UStags' prefix and/or suffix sequences that contain cysteine(s) in conjunction with sequences of the UStags-specified database proteins is shown to enable the unambigious determination of disulfide bonds. Using this method, we identified the intermolecular and intramolecular disulfides in human blood plasma peptidome peptides that have molecular weights of up to approximately 10 kDa.
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