A Variety of Activation Methods Employed in 'Activated-Ion' Electron Capture Dissociation Mass Spectrometry: A Test against Bovine Ubiquitin 7+ Ions

摘要

Fragmentation efficiencies of various 'activated-ion' electron capture dissociation (AI-ECD) methods are compared for a model system of bovine ubiquitin 7+ cations.In AI-ECD studies,sufficient internal energy was given to protein cations prior to ECD application using IR laser radiation,collisions,blackbody radiation,or in-beam collisions,in turn.The added energy was utilized in increasing the population of the precursor ions with less intra-molecular noncovalent bonds or enhancing thermal fluctuations of the protein cations.Removal of noncovalent bonds resulted in extended structures,which are ECD friendly.Under their best conditions,a variety of activation methods showed a similar effectiveness in ECD fragmentation.In terms of the number of fragmented inter-residue bonds,IR laser/blackbody infrared radiation and 'in-beam' activation were almost equally efficient with approx 70% sequence coverage,while collisions were less productive.In particular,'in-beam' activation showed an excellent effectiveness in characterizing a pre-fractionated single kind of protein species.However,its inherent procedure did not allow for isolation of the protein cations of interest.