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Electron Capture Dissociation of Hydrogen- Deficient Peptide Radical Cations

Kalli, Anastasia and Hess, Sonja (2012) Electron Capture Dissociation of Hydrogen- Deficient Peptide Radical Cations. Journal of the American Society for Mass Spectrometry, 23 (10). pp. 1729-1740. ISSN 1044-0305. doi:10.1007/s13361-012-0433-8.

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Hydrogen-deficient peptide radical cations exhibit fascinating gas phase chemistry, which is governed by radical driven dissociation and, in many cases, by a combination of radical and charge driven fragmentation. Here we examine electron capture dissociation (ECD) of doubly, [M + H]^(2+•), and triply, [M + 2H]^(3+•), charged hydrogen-deficient species, aiming to investigate the effect of a hydrogen-deficient radical site on the ECD outcome and characterize the dissociation pathways of hydrogen-deficient species in ECD. ECD of [M + H]^(2+•) and [M + 2H]^(3+•) precursor ions resulted in efficient electron capture by the hydrogen-deficient species. However, the intensities of c- and z-type product ions were reduced, compared with those observed for the even electron species, indicating suppression of N–Cα backbone bond cleavages. We postulate that radical recombination occurs after the initial electron capture event leading to a stable even electron intermediate, which does not trigger N–Cα bond dissociations. Although the intensities of c- and z-type product ions were reduced, the number of backbone bond cleavages remained largely unaffected between the ECD spectra of the even electron and hydrogen-deficient species. We hypothesize that a small ion population exist as a biradical, which can trigger N–C_α bond cleavages. Alternatively, radical recombination and N–C_α bond cleavages can be in competition, with radical recombination being the dominant pathway and N–C_α cleavages occurring to a lesser degree. Formation of b- and y-type ions observed for two of the hydrogendeficient peptides examined is also discussed.

Item Type:Article
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Hess, Sonja0000-0002-5904-9816
Additional Information:© 2012 American Society for Mass Spectrometry. Received: 11 April 2012; Revised: 5 June 2012; Accepted: 12 June 2012; Published online: 2 August 2012. The authors acknowledge support for this work by the Beckman Institute and the Gordon and Betty Moore Foundation.
Funding AgencyGrant Number
Caltech Beckman InstituteUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:Electron capture dissociation; Hydrogen-deficient peptide radical cations; Radical recombination; Suppressed N–Cα Bond Cleavages
Issue or Number:10
Record Number:CaltechAUTHORS:20121109-113036902
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35388
Deposited By: Jason Perez
Deposited On:09 Nov 2012 21:32
Last Modified:09 Nov 2021 23:14

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