Non-zwitterionic structures of aliphatic-only peptides mediated the formation and dissociation of gas phase radical cations
✍ Scribed by Corey N. W. Lam; Eric D. L. Ruan; C. Y. Ma; Ivan K. Chu
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 217 KB
- Volume
- 41
- Category
- Article
- ISSN
- 1076-5174
- DOI
- 10.1002/jms.1052
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✦ Synopsis
Abstract
We have investigated how the non‐zwitterionic and zwitterionic structures of aliphatic‐only tripeptides affect the formation and dissociation of peptide radical cations in the gas phase. The non‐zwitterionic forms of the aliphatic‐only peptides in their metal complexes play an important role in determining whether the electron transfer pathway predominates. We extended this study by synthesizing permanent non‐zwitterionic and zwitterionic forms of aliphatic‐only peptide radical cations and exploring their reactivities in the gas phase. Collision‐induced dissociation spectra demonstrated the feasibility of generating both non‐zwitterionic and zwitterionic forms. Radical cations in zwitterionic forms may indeed mediate the β and γ carbon–carbon bond cleavages of leucine and isoleucine side chains from the GlyGlyXle radical peptides; this feature allows leucine and isoleucine residues to be distinguished unambiguously. Copyright © 2006 John Wiley & Sons, Ltd.