Peptide cation, multiply-charged

Transient intermediates arising by radical additions to the amide bond have been studied recently in an effort to explain the complex processes occurring in electron-capture dissociation of multiply charged peptide and protein cations [192]. The amino(hydroxy)methyl radical, HC(OH)NH2 (64), is a prototypical species that represents the simplest model for radical additions to peptide bonds. Radical 64 was generated from cation 64+ which in turn was prepared by... 

These radical cations are then injected into the trap where they are mixed with the multiply charged peptide cations to which an electron is then transferred, leading to their direct dissociation into c- and z-type ions by the same mechanism responsible for ECD. The process is rapid (milliseconds) and quite compatible with the... 

Ogorzalek Loo, R. R. Smith, R. D. Proton transfer reactions of multiply charged peptide and protein cations and anions. J. Mass Spectrom. 1995, 30, 339-347. 

Mote recently, ETD, a dissociation technique very similar to ECD, was introduced for peptide/protein sequencing [56-58]. In ETD, multiply-chaiged cations react with an anion radical (A, e.g., SO2, SFg", anthracene, fluoranthene), leading to electron transfer and the generation of both odd- and even-electron fragments and molecular species with lower charge states as follows ... 

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