Ion mobility-mass spectrometry applied to cyclic peptide analysis: conformational preferences of gramicidin S and linear analogs in the gas phase. Academic Article uri icon


  • In this paper, we present an investigation of the gas-phase structural differences between cyclic and linear peptide ions by matrix-assisted laser desorption ionization-ion mobility-mass spectrometry. Specifically, data is shown for gramicidin S (cyclo-VOLFPVOLFP where phenylalanines are D rather than L-type amino acids and the O designates the non-standard amino acid ornithine) and five linear gramicidin S analogues. Results are interpreted as evidence for a beta-sheet (or beta-hairpin) conformational preference in both linear-protonated and sodiated-cyclic gramicidin S gas-phase peptides, and a preference for the protonated-cyclic peptide to adopt a collapsed, random coil-type conformation. A comparison with solution-phase circular dichroism measurements is performed, and structures similar to those observed in the gas phase appear to be favored in low-dielectric solvents such as 2,2,2-triflouroethanol. The utility of ion mobility-mass spectrometry (IM-MS) as a means of rapidly distinguishing between linear and cyclic peptide forms in also discussed.

published proceedings

  • J Am Soc Mass Spectrom

author list (cited authors)

  • Ruotolo, B. T., Tate, C. C., & Russell, D. H.

citation count

  • 60

complete list of authors

  • Ruotolo, Brandon T||Tate, Colby C||Russell, David H

publication date

  • June 2004