INIFTA   05425
INSTITUTO DE INVESTIGACIONES FISICO-QUIMICAS TEORICAS Y APLICADAS
Unidad Ejecutora - UE
artículos
Título:
Electron transfer processes induced by the triplet state of pterins in aqueous solutions
Autor/es:
M. LAURA DÁNTOLA, MARIANA VIGNONI, CONSTANZA GONZÁLEZ, CAROLINA LORENTE, PATRICIA VICENDO, ESTHER OLIVEROS, ANDRÉS H. THOMAS
Revista:
FREE RADICAL BIOLOGY AND MEDICINE
Editorial:
ELSEVIER SCIENCE INC
Referencias:
Año: 2010 vol. 49 p. 1014 - 1022
ISSN:
0891-5849
Resumen:
Pterins (Pt)
are heterocyclic compounds widespread in living systems. They participate in
relevant biological processes, such as metabolic redox reactions, and can
photoinduce the oxidation of biomolecules through electron-transfer mechanisms.
We have investigated the electron-transfer pathways initiated by excited states
of pterin (Ptr) and 6-methylpterin (Mep), selected as model compounds. The
experiments were carried out in aqueous solutions under continuous UV-A
irradiation, in the presence and in the absence of ethylenediaminetetraacetic
acid (EDTA), used as an electron donor. The reactions were followed by UV/Vis
spectrophotometry, HPLC, and an enzymatic method for H2O2 determination. The
formation of the superoxide anion (O2 −) was investigated by electron
paramagnetic resonancespin trapping. The triplet excited states of Ptr and Mep
are efficient electron acceptors, able to oxidize a Pt molecule in its ground
state. The resulting radical anion (Pt−) reacts with dissolved O2 to yield O2
−, regenerating the pterin. In the presence of EDTA, this reaction competes
efficiently with the anaerobic reaction between Pt− and EDTA+, yielding the
corresponding stable dihydroderivatives H2Pt. The effects of EDTA and dissolved
O2 concentrations on the efficiencies of the different competing pathways were
analyzed.