Mass spectrometric and bio-computational analysis of multiply charged RNase S gas phase complexes obtained by electrospray ionization from varying in-solution equilibrium conditions

In this project we investigate the influence of a solvent's composition on the stability of desorbed and multiply charged RNase S ions by analyzing gas phase dissociation reactions triggered by collision induced dissociation (CID) of multiply charged complex ions. RNase S was dissolved in ESI-compatible buffers with either an increasing content of organic co-solvent or with different pH. Direct transition of all ions from the in-solution components is followed by CID of the non-covalent RNase S complex and by quantitative analysis of the dissociation products. From normalized ion abundances are determined the apparent kinetic and apparent thermodynamic gas phase complex properties. The stability of RNase S in the gas phase is independent from the in-solution equilibrium but sensitive to differences in charge states.