Multiply-sodiated ions were observed by electrospraying oligoglycines and their N-acetylated and O-amidated derivatives in the presence of sodium hydroxide. These ions have all their hydrogens in the peptide linkages replaced by sodiums; one hydrogen in the C-terminal amide and the hydrogen in the C-terminal carboxylic group are also replaced. The N-terminal amine hydrogens are unreactive. These results are consistent with earlier postulations [Int. J. Mass Spectrom. 192 (1999) 303, J. Am. Soc. Mass Spectrom. 11 (2000) 967], and apparently confirm the gas-phase origin of these ions (formed in the electrospray source and/or the lens region). Collision-induced dissociation of multiply-sodiated oligoglycines showed that the major product ions are C-terminal ions.

Gas-phase reactions, Oligoglycines, Sodium substitutions
International Journal of Mass Spectrometry
Department of Chemistry

Grewal, R.Natasha (R. Natasha), Aribi, H.E. (Houssain El), Smith, J. C, Rodriquez, C.F. (Christopher F), Hopkinson, A.C. (Alan C), & Siu, K.W.Michael (K. W.Michael). (2002). Multiple substitution of protons by sodium ions in sodiated oligoglycines. International Journal of Mass Spectrometry, 219(1), 89–99. doi:10.1016/S1387-3806(02)00561-4