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Updated: Jan 5, 2026

Ubiquitin Chain Analysis by Parallel Reaction Monitoring
Published on: June 17, 2020
QCMS2 as a new method for providing insight into peptide fragmentation: The influence of the side-chain and
Julie Cautereels1, Nils Van Hee1, Sneha Chatterjee1
1Department of Chemistry, University of Antwerp, Antwerp, Belgium.
Abstract:
The identification of peptides and proteins from tandem mass spectra is a difficult task and multiple tools have been developed to aid this identification. We present a new method called quantum chemical mass spectrometry for materials science (QCMS2 ), which is based on quantum chemical calculations of bond orders, reaction, and transition-state energies at the DFT/B3LYP/6-311+G* level of theory. The method was used to describe the fragmentation pathways of five X-His-Ser tripeptides with X = Asn, Asp, Glu, Ser, and Trp, thereby focusing on the influence of the side chain and inter-side-chain interactions on the fragmentation. The main features in the mass spectra of the five tripeptides were correctly reproduced, and a number of fragments were assigned to fragmentations involving the side chain and the influence of inter-side-chain interactions. Product ion spectra were recorded to evaluate the capabilities and limitations of QCMS2 and a number of conventional tools.
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