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%).

We extend here a set of earlier articles that deal with irreversible processes across a thin boundary separating a system from its surroundings. We consider the transfer of heat and material when the system and reservoir are held at constant volume, and the temperatures (T) and chemical potentials (μ) differ by arbitrary amounts in the two parts of the compound system. Three distinct time variations for changing temperature and composition in the system are adopted. Although for any specified change of state the entropies associated with the transfer of heat and matter are quite different in the three cases, the overall entropy change remains the same, as is consistent with entropy being a function of state. The relation of the present approach to standard methodology is discussed.

No abstract

No abstract

No abstract