Top-Down Charge Transfer Dissociation (CTD) of Gas-Phase Insulin: Evidence of a One-Step, Two-Electron Oxidation Mechanism.

ABSTRACT: Top-down analyses of protonated insulin cations of charge states of 4+, 5+, or 6+ were performed by exposing the isolated precursor ions to a beam of helium cations with kinetic energy of more than 6 keV, in a technique termed charge transfer dissociation (CTD). The ~100 ms charge transfer reaction resulted in approximately 20% conversion efficiency to other intact charge exchange products (CTnoD), and a range of low abundance fragment ions. To increase backbone and sulfide cleavages, and to provide better structural information than straightforward MS² CTD, the CTnoD oxidized products were isolated and subjected to collisional activation at the MS³ level. The MS³ CTD/CID reaction effectively broke the disulfide linkages, separated the two chains, and yield

SUBMITTER: Li P 

PROVIDER: S-EPMC5803485 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature