Fragmentation of the DNA Lesion 8-oxo-Guanine by Low-Energy Electrons

Autor(es)

Vetritti, Leonardo ; Kopyra, Janina ; Wierzbicka, Paulina ; Varella, Maïrcio T. do N.

• Tipo de documento: Artigo Científico
• Fonte: Journal of Physical Chemistry A; v. 127, n. 36, p. 9-pg., 2023-09-04.

Resumo

8-oxo-Guanine is a mutagenic lesion produced by reactions involving reactive oxygen species and guanine in DNA. Its production induces mispairing between the canonical nucleobases during DNA replication such that various types of cancers are associated with the DNA lesion. Since radiation therapy is used in some cases, the interaction of low-energy electrons with 8-oxo-guanine can in turn produce other reactive species, which in principle could have either a detrimental or protective effect on the organism. Motivated by these facts, we report a comparative experimental study of electron-induced fragmentation of guanine and 8-oxo-guanine, along with a theoretical study of the pi* shape resonances and bound anion states, which may trigger those dissociation reactions. The electron-induced fragmentation of 8-oxo-guanine is remarkably distinct from the native form. More complex reactions were observed for the oxidized species, which may produce several anion fragments at very low energies (similar to 0 eV). The dehydrogenated parent anion, which is already a minor fragment in guanine, was completely suppressed in 8-oxo-guanine. The calculated thermodynamical thresholds also suggest that NH2 elimination in guanine, at sub-excitation energies, proceeds via a complex reaction involving rearrangement steps. (AU)

• Processo FAPESP: 20/16155-7 - Modelos moleculares para ciências positrônica, biológica e de materiais
• Beneficiário: Márcio Teixeira do Nascimento Varella
• Modalidade de apoio: Auxílio à Pesquisa - Regular