Unraveling the degradation mechanism of purine nucleotides photosensitized by pterins: the role of charge-transfer steps

MARIANA P. SERRANO; CAROLINA LORENTE; CLAUDIO D. BORSARELLI; ANDRÉS H. THOMAS

Chemphyschem

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2015 vol. 16 p. 2244 - 2252

1439-4235

Photosensitizedreactions contribute to the generation of skin cancer and are used in manyapplications. The photosensitizers may act through different mechanisms. It iscurrently accepted that if the photosensitizer generates singlet molecularoxygen (1O2) upon irradiation, the target molecule isable to be oxidized by this ROS and the reaction needs dissolved O2to take place, the reaction is named a 1O2-mediatedoxidation (type II mechanism). However, this assumption is not always precise. Asan example of this type of case, we present here a study on the degradation of2´-deoxyguanosine 5´-monophosphate (dGMP) photosensitized by pterin. Wepropose a general mechanism to explain why the degradation of biological targets, such asnucleotides, photosensitized by pterins, naturally occurring 1O2photosensitizers, takes place through an electron-transfer initiated process(type I mechanism), being almost negligible the contribution of the 1O2-mediatedoxidation.