Collision-Induced Dissociation of Diazirine-Labeled Peptide Ions. Evidence for Brønsted-Acid Assisted Elimination of Nitrogen

Content Provider	Semantic Scholar
Author	Marek, Aleš Tureček, František
Copyright Year	2014
Abstract	AbstractGas-phase dissociations were investigated for several peptide ions containing the Gly-Leu* N-terminal motif where Leu* was a modified norleucine residue containing the photolabile diazirine ring. Collisional activation of gas-phase peptide cations resulted in facile N2 elimination that competed with backbone dissociations. A free lysine ammonium group can act as a Brønsted acid to facilitate N2 elimination. This dissociation was accompanied by insertion of a lysine proton in the side chain of the photoleucine residue, as established by deuterium labeling and gas-phase sequencing of the products. Electron structure calculations were used to provide structures and energies of reactants, intermediates, and transition states for Gly-Leu*-Gly-Gly-Lys amide ions that were combined with RRKM calculations of unimolecular rate constants. The calculations indicated that Brønsted acid-catalyzed eliminations were kinetically preferred over direct loss of N2 from the diazirine ring. Mechanisms are proposed to explain the proton-initiated reactions and discuss the reaction products. The non-catalyzed diazirine ring cleavage and N2 loss is proposed as a thermometer dissociation for peptide ion dissociations. Fig. aᅟ
Starting Page	778
Ending Page	789
Page Count	12
File Format	PDF HTM / HTML
DOI	10.1007/s13361-014-0832-0
Alternate Webpage(s)	https://static-content.springer.com/esm/art:10.1007%2Fs13361-014-0832-0/MediaObjects/13361_2014_832_MOESM1_ESM.pdf
PubMed reference number	24549894
Alternate Webpage(s)	https://doi.org/10.1007/s13361-014-0832-0
Journal	Medline
Volume Number	25
Journal	Journal of The American Society for Mass Spectrometry
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article