Suchergebnisse

[EN] The photochemistry of the DNA biomacromolecule is an issue of paramount importance as it is part of the etiology of skin cancer development, being ultraviolet sunlight radiation the most relevant environmental carcinogen. Herein, we demonstrate the potential of pterin, an endogenous compound, to form covalent adduct under UVA irradiation with a short thymine oligomer as well as with the whole DNA polymer. Our approach is based on the spectroscopic features of pterin, which allow, by monitoring specific absorption or emission wavelengths, the following-up of the covalent binding. The results are confirmed by HPLC coupled with mass spectrometry, revealing the attachment of one or two pterin units to the homothymine 5-mer oligonucleotide. Altogether the findings point toward the role of pterin as endogenous sensitizer and genotoxic compound. ; The present work was partially supported by Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET-Grant PIP 112-200901-0304), Agencia de Promocion Cientifica y Tecnologica (ANPCyT-Grant PICT-2012-0508), Universidad Nacional de La Plata (UNLP-Grant X712). Funding from the Programa CSIC de Cooperacion Cientifica para el Desarrollo (iCOOPLight project ref 20105CD0017) and Spanish Government (CTQ2015-70164-P) are gratefully acknowledged. S.E.R. thanks ANPCyT and CONICET for doctoral research fellowships. M.G.T thanks CONICET for postdoctoral fellowship. C.L. and A.H.T. are research members of CONICET. The authors thank Dr. Mariana Vignoni (INIFTA, CONICET) and Nathalie Martins-Froment of the Service Commun de Spectrometrie de Masse (FR2599), Universite de Toulouse III (Paul Sabatier) for their crucial contributions in mass spectrometry measurements. ; Estébanez, S.; Lorente, C.; Gaspar Tosato, M.; Miranda Alonso, MÁ.; Marín García, ML.; Lhiaubet, VL.; Thomas, AH. (2019). Photochemical formation of a fluorescent thymidine-pterin adduct in DNA. Dyes and Pigments. 160:624-632. https://doi.org/10.1016/j.dyepig.2018.08.024 ; S ; 624 ; 632 ; 160

[EN] The main goal of the present work was to investigate the damages photoinduced by pterin (Ptr), an endogenous photosensitizer present in human skin under pathological conditions, on a globular protein such as ubiquitin (Ub). Particular attention has been paid on the formation of covalent adducts between Ptr and the protein that can behave as photoantigen and provoke an immune system response. Here, a multifaceted approach including UV-visible spectrophotometry, fluorescence spectroscopy, electrophoresis, size exclusion chromatography, and mass spectrometry is used to establish the Ub changes triggered by UV-A irradiation in the presence of Ptr. Under anaerobic conditions, the only reaction corresponds to the formation of a covalently bound Ptr-Ub adduct that retains the spectroscopic properties of the free photosensitizer. A more complex scheme is observed in air-equilibrated solutions with the occurrence of three different processes, that is, formation of a Ptr-Ub adduct, dimerization, and fragmentation of the protein. ; The present work was partially supported by Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET-Grants PIP 112-200901-0304 and PIP 11220120100072CO), Agencia de Promocion Cientifica y Tecnologica (ANPCyT-Grants PICT-2015-1988 and PICT 2016-00130), Universidad Nacional de La Plata (UNLP-Grant X712 and X840), and Universidad de Buenos Aires (UBA-Grant 000110BA). Funding from the Programa CSIC de Cooperacion Cientifica para el Desarrollo (iCOOPLight project ref 20105CD0017) and Spanish government (PGC2018-096684-B-I00) is gratefully acknowledged. The Ultraflex II (Bruker) TOF/TOF mass spectrometer was supported by a grant from ANPCYT, PME2003 No. 125, and the ESI-MS Q Exactive, Thermo Scientific, by a grant from ANPCYT, PME2011-PPL2-0009, CEQUIBIEM, DQB, FCEN, UBA. The proteomic analysis was performed in the proteomics facility of SCSIE University of Valencia. This proteomics laboratory is a member of Proteored, PRB3 and is supported by grant PT17/0019, of the PE I+D+i ...