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High‐energy collision‐induced dissociation of histidine ions [His + H] + and [His − H] − and histidine dimer [His 2 + H] +
Author(s) -
Khreis Jusuf M.,
Reitshammer Julia,
Vizcaino Violaine,
Klawitter Kevin,
Feketeová Linda,
Denifl Stephan
Publication year - 2017
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.8027
Subject(s) - chemistry , dissociation (chemistry) , dimer , protonation , collision induced dissociation , imidazole , fragmentation (computing) , ion , histidine , crystallography , tetramer , deprotonation , mass spectrometry , tandem mass spectrometry , stereochemistry , organic chemistry , chromatography , computer science , enzyme , operating system
Rationale Histidine (His) is an essential amino acid, whose side group consists of an aromatic imidazole moiety that can bind a proton or metal cation and act as a donor in intermolecular interactions in many biological processes. While the dissociation of His monomer ions is well known, information on the kinetic energy released in the dissociation is missing. Methods Using a new home‐built electrospray ionization (ESI) source adapted to a double‐focusing mass spectrometer of BE geometry, we investigated the fragmentation reactions of protonated and deprotonated His, [His + H] + and [His − H] − , and the protonated His dimer [His 2 + H] + , accelerated to 6 keV in a high‐energy collision with helium gas. We evaluated the kinetic energy release (KER) for the observed dissociation channels. Results ESI of His solution in positive mode led to the formation of His clusters [His n + H] + , n = 1–6, with notably enhanced stability of the tetramer. [His + H] + dissociates predominantly by loss of (H 2 O + CO) with a KER of 278 meV, while the dominant dissociation channel of [His − H] − involves loss of NH 3 with a high KER of 769 meV. Dissociation of [His 2 + H] + is dominated by loss of the monomer but smaller losses are also observed. Conclusions The KER for HCOOH loss from both [His + H] + and [His − H] − is similar at 278 and 249 meV, respectively, which suggests that the collision‐induced dissociation takes place via a similar mechanism. The loss of COOH and C 2 H 5 NO 2 from the dimer suggests that the dimer of His binds through a shared proton between the imidazole moieties.