Volume 150, 2011

Spectroscopy of mobility-selected biomolecular ions

Abstract

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 techniques as it exhibits a considerable degree of conformational heterogeneity that results in a highly congested electronic spectrum. Our results demonstrate the feasibility 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.

Article information

Article type
Paper
Submitted
26 Nov 2010
Accepted
04 Jan 2011
First published
05 May 2011

Faraday Discuss., 2011,150, 243-255

Spectroscopy of mobility-selected biomolecular ions

G. Papadopoulos, A. Svendsen, O. V. Boyarkin and T. R. Rizzo, Faraday Discuss., 2011, 150, 243 DOI: 10.1039/C0FD00004C

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