www.chembiochem.org Accepted Article A Journal of Title: Non-Enzymatic Oligomerization of 3',5' Cyclic CMP Induced by Proton- and UV-Irradiation Hints at a Non-Fastidious Origin of RNA Authors: Giovanna Costanzo, Alessandra Giorgi, Anita Scipioni, Anna Maria Timperio, Carmine Mancone, Marco Tripodi, Michail Kapralov, Eugene Krasavin, Holger Kruse, Jiri Sponer, Judit E. Sponer, Vaclav Ranc, Michal Otyepka, Samanta Pino, and Ernesto Di Mauro This manuscript has been accepted after peer review and appears as an Accepted Article online prior to editing, proofing, and formal publication of the final Version of Record (VoR). This work is currently citable by using the Digital Object Identifier (DOI) given below. The VoR will be published online in Early View as soon as possible and may be different to this Accepted Article as a result of editing. Readers should obtain the VoR from the journal website shown below when it is published to ensure accuracy of information. The authors are responsible for the content of this Accepted Article. To be cited as: ChemBioChem 10.1002/cbic.201700122 Link to VoR: http://dx.doi.org/10.1002/cbic.201700122