Competitive Hydrogen Atom Migrations Accompanying Cascade Dissociations of Peptide Cation-Radicals of the z^+• Type.

ABSTRACT: We report a combined experimental and computational study of energy-resolved collision-induced dissociation (ER-CID) and time-resolved infrared multiphoton dissociation (TR-IRMPD) of z₄ ions prepared by electron transfer dissociation of peptide (Ala-Ala-Asn-Ala-Arg + 2H)²⁺ ions. The z₄ cation-radicals, ^•ANAR⁺, undergo competitive dissociations by backbone cleavage and loss of a CONH₂ radical from the Asn side chain. The backbone cleavage proceeds by radical-assisted dissociation of the Asn C_α-CO bond, forming an x₂ ion intermediate which rapidly dissociates by HNCO elimination to yield a stable z₂ fragment ion, ^•AR⁺

SUBMITTER: Ledvina AR 

PROVIDER: S-EPMC4380023 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature