Spectroscopy of mobility-selected biomolecular ions

• Published in: Faraday Discussions (ISSN: 0301-7249), vol. 150, p. 243
• Publication date: 2011

We describe here experiments that combine differential ion mobility, which separates conformational isomers of biomolecular ions, with electronic spectroscopy in a cold, radio-frequency ion trap. Although the low temperature attainable in a cold ion trap greatly simplifies the electronic spectra of large molecules, conformational heterogeneity can still be a significant source of congestion, complicating spectroscopic analysis. We demonstrate here that using differential ion mobility to separate gas-phase peptide conformers before injecting them into a cold ion trap allows one to decompose a dense spectrum into contributions from different conformational families. In the inverse sense, cold ion spectroscopy can be used as a conformation-specific detector for ion mobility, allowing one to separate an unresolved peak into contributions from different conformational families. The doubly protonated peptide bradykinin serves as a good test case for the marriage of these two techiques as it exhibits a considerable degree of conformational heterogeneity that results in a highly congested electronic spectrum. Our results demonstrate the feasiblity and advantages of directly coupling ion mobility with spectroscopy and provide a diagnostic of conformational isomerization of this peptide after being produced in the gas phase by electrospray.

Keywords: laser spectroscopy, mass spectrometry, ion mobility

Reference

• EPFL-ARTICLE-162452
• doi:10.1039/C0FD00004C
• View record in Web of Science

Record created on 2011-01-20, modified on 2017-05-12