rrelation Between the Charge of Proteins in Solution and in the Gas Phase Investigated by Protein Charge Ladders, Capillary Electrophoresis, and Electrospray Ionization Mass Spectrometry", Carbeck, 3. 0., Severs, J. C., Gao, J., Wu, Q., Smith, R. D. and Whitesides, G. M., J. Phys. Chem. 8, 1998, 102, 10596-10601.