Cytosine (C4H5N3O) is a nucleobase that is paired with guanine in DNA and RNA molecules. In living organisms, several isomeric forms of cytosine can coexist. Although they are close in energy, their chemical properties and, therefore, their biological functions can be completely different, which makes their study quite challenging.
The researchers in the consortium were able to identify five isomers of cytosine by combining ab initio simulations and experiments carried out on the DESIRS (Dichroism and Spectroscopy through Interaction with Synchrotron Radiation) beamline of the SOLEIL synchrotron facility, equipped with an electron-ion coincidence double-imaging spectrometer. They were able to determine thermochemical and structural data for these isomers. Their results provide valuable information for the scientists to deepen their understanding of the chemical reactivity of DNA or RNA induced by either natural or therapeutic radiation.