INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
UV photoionization of cytosine catalyzed by Ag+
Autor/es:
GERALDINE FÉRAUD; GILLES GRÉGOIRE; MATÍAS BERDAKIN; CHRISTOPHE JOUVET; GUSTAVO A. PINO; MARTÍN I. TACCONE; CLAUDE DEDONDER-LARDEUX; MICHEL BROQUIER
Lugar:
Mendoza
Reunión:
Congreso; 9th International Meeting on Photodynamics and Related Aspects; 2016
Resumen:
The interaction of DNA with several cations is of great importance in nature, and in many cases, it has been recognized to alter the fidelity of DNA synthesis and those cations have been considered mutagens or carcinogens. One of the most interesting examples is Ag+ whose AgNO3 salt has been considered as mutagen class I; however, silver is extensively used as an antimicrobial agent.The joint effect of UV light and Ag+ interaction with DNA bases is still unknown. It has been recently reported that Ag+ can induce the formation of non-canonical DNA pairs such as silver mediated cytosine (Cyt) pair (Cyt2Ag+)1-2, which exhibit a long excited state lifetime in comparison with the excited state lifetime of isolated Cyt3 meaning that the effect of this cation on the electronic properties of the DNA bases could be very important.In this work, we study the spectroscopy of Cytosine-Ag+ (CytAg+) complex by means of UV photofragmentation and methods, on the gas phase, as a reductionist approach to gain information about the effect of Ag+ on the optical properties of the DNA bases and especially on the mutagenic role of this cation.We have observed that the photoexcitation of the CytAg+ complex at low energy (315-282) nm efficiently leads to ionized cytosine (Cyt+) as the single product, which is completely different from the results observed in the ground state fragmentation of the CytAg+ complex, achieved by IR-MPD leading to the loss of the HNCO neutral fragments as the main fragmentation channel.4 The figure shows the mass spectrum obtained with the photo-dissociation laser tuned to 315 nm. This result strongly suggests that the excited state is a Charge Transfer (CT) state that involves the promotion of an electron from the π orbital of Cyt is promoted to Ag+, confirmed by ab-initio calculations at the TD-DFT/B3LYP and RI-ADC(2) theory level using the SV(P) basis set.1) H. Urata, E. Yamaguchi, Y. Nakamuraa and S. Wadaa, Chem. Commun., 2011,47, 941-943.2) M. Berdakin, V. Steinmetz, P. Maitre, and G. A. Pino, J. Phys. Chem. A, 2014 118, 3804.3) M. Berdakin, G. Féraud, C. Dedonder-Lardeux, C. Jouvet, and G. A. Pino, J. Phys. Chem. Lett., 2014, 5, 2295.4) M. Berdakin, V. Steinmetz, P. Maitreb and G. A. Pino, Phys. Chem. Chem. Phys., 2015,17, 25915-25924