Electron transfer dissociation (ETD) is an analytically useful tool for primary 
structure interrogation of intact proteins, but its utility is limited by 
higher-order reactions with the products. To inhibit these higher-order 
reactions, first-generation fragment ions are kinetically excited by applying an 
experimentally tailored parallel ion parking waveform during ETD (ETD-PIP). In 
combination with subsequent ion/ion proton transfer reactions, 
precursor-to-product conversion was maximized as evidenced by the consumption of 
more than 90% of the 21 kDa Protein G precursor to form ETD product ions. The 
employment of ETD-PIP increased sequence coverage to 90% from 80% with standard 
ETD. Additionally, the inhibition of sequential electron transfers was reflected 
in the high number of complementary ion pairs from ETD-PIP (90%) compared to 
standard ETD (39%).