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Issue 16, 2016
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Multiple gas-phase conformations of proline-containing peptides: is it always cis/trans isomerization?

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Abstract

Ion mobility-mass spectrometry (IM-MS) is often employed to look at the secondary, tertiary, and quaternary structures of naked peptides and proteins in the gas-phase. Recently, it has offered a unique glimpse into proline-containing peptides and their cis/trans Xxx-Pro isomers. An experimental “signature” has been identified wherein a proline-containing peptide has its Pro residues substituted with another amino acid and the presence or absence of conformations in the IM-MS spectra is observed. Despite the high probability that one could attribute these conformations to cis/trans isomers, it is also possible that cis/trans isomers are not the cause of the additional conformations in proline-containing peptides. However, the experimental evidence of such a system has not been demonstrated or reported. Herein, we present the IM-MS analysis of Neuropeptide Y's wild-type (WT) signal sequence and Leu7Pro (L7P) mutant. Although comparison of arrival times and collision cross-sections of [M + 4H]4+ ions yields the cis/trans “signature”, molecular dynamics indicates that a cis-Pro7 is not very stable and that trans-Pro7 conformations of the same cross-section arise with equal frequency. We believe that this work further underscores the importance of theoretical calculations in IM-MS structural assignments.

Graphical abstract: Multiple gas-phase conformations of proline-containing peptides: is it always cis/trans isomerization?

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Publication details

The article was received on 28 Apr 2015, accepted on 12 Jul 2016 and first published on 12 Jul 2016


Article type: Communication
DOI: 10.1039/C5AN00835B
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Citation: Analyst, 2016,141, 4863-4869
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    Multiple gas-phase conformations of proline-containing peptides: is it always cis/trans isomerization?

    C. B. Lietz, Z. Chen, C. Yun Son, X. Pang, Q. Cui and L. Li, Analyst, 2016, 141, 4863
    DOI: 10.1039/C5AN00835B

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