On the survival of peptide cations after electron capture: role of internal hydrogen bonding and microsolvation

Chakraborty, Tapas ; Holm, Anne I. S. ; Hvelplund, Preben ; Nielsen, Steen Brøndsted ; Poully, Jean-Christophe ; Worm, Esben S. ; Williams, Evan R. (2006) On the survival of peptide cations after electron capture: role of internal hydrogen bonding and microsolvation Journal of the American Society for Mass Spectrometry, 17 (12). pp. 1675-1680. ISSN 1044-0305

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Official URL: http://link.springer.com/article/10.1016/j.jasms.2...

Related URL: http://dx.doi.org/10.1016/j.jasms.2006.07.018


Electron capture by both bare and microsolvated small peptide dications was investigated by colliding these ions with sodium vapor in an accelerator mass spectrometer to provide insight into processes that occur on the microsecond time frame. Survival of the intact peptide monocation after electron capture depends strongly on molecular size. For dipeptides, no intact reduced species were observed; the predominant ions correspond to loss of hydrogen and ammonia. In contrast, the intact reduced species was observed for larger peptides. Calculated structures indicate that the diprotonated dipeptide ions form largely extended structures with low probability of internal ionic hydrogen bonding (i.e., charge solvation) whereas internal ionic H-bonding occurs extensively for larger peptide dications. Solvation of the peptide ions with between one to seven methanol molecules reduces the total extent of H loss even for dipeptides where intact reduced species can survive more than a microsecond after electron capture. The yield of ions corresponding to cleavage of N-Cα bonds (c+ and z ions) does not depend strongly on peptide size but decreases with the extent of microsolvation for the dipeptide dications. H-bonding appears to play an important role for the survival of the intact reduced ions but less so for the formation of c+ and z+. ions. Our results indicate that electron capture predominantly occurs at the ammonium groups (at least 70 to 80%), and provides important new insights into the electron capture dissociation process.

Item Type:Article
Source:Copyright of this article belongs to Elsevier Science.
ID Code:100543
Deposited On:06 Dec 2016 12:20
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