Mass-resolved electronic circular dichroism ion spectroscopy

Steven Daly (1) , Frederic Rosu (2) , Valérie Gabelica (1)

1 ARNA - Acides Nucléiques : Régulations Naturelle et Artificielle
2 Soutien à la Recherche de l'Institut Européen de Chimie Biologique

DNA and proteins are chiral: their three-dimensional structure cannot be superimposed with its mirror image. Circular dichroism spectroscopy is widely used to characterize chiral compounds, but data interpretation is difficult in the case of mixtures. We recorded the electronic circular dichroism spectra of DNA helices separated in a mass spectrometer. We studied guanine-rich strands having various secondary structures, electrosprayed them as negative ions, irradiated them with a UV-vis nanosecond OPO laser, and measured the difference in electron photodetachment efficiency between left and right circularly polarized light. The reconstructed circular dichroism ion spectra resemble their solution counterparts, thereby allowing us to assign the DNA helical topology. The ability to measure circular dichroism directly on biomolecular ions expands the capabilities of mass spectrometry for structural analysis.

Domains: Biophysics; Theoretical and/or physical chemistry; Analytical chemistry; Chemical Physics [physics.chem-ph]; Biological Physics [physics.bio-ph]; Structural Biology [q-bio.BM]; Biochemistry [q-bio.BM]

Steven Daly, Frederic Rosu, Valérie Gabelica. Mass-resolved electronic circular dichroism ion spectroscopy. Science, 2020, 368 (6498), pp.1465-1468. ⟨10.1126/science.abb1822⟩. ⟨hal-02882085⟩