Tryptophan Oxidation Photosensitizided by Pterin
Pterins are normal components of cells and they have been previously identified as good photosensitizers under UV-A irradiation, inducing DNA damage and oxidation of nucleotides. In this work, we have investigated the ability of pterin (Ptr), the parent compound of oxidized pterins, to photosensitiz...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2013 |
| País: | Argentina |
| Institución: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repositorio: | CONICET Digital (CONICET) |
| Idioma: | inglés |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/4817 |
| Acceso en línea: | http://hdl.handle.net/11336/4817 |
| Access Level: | acceso abierto |
| Palabra clave: | Photosensitization Tryptophan Pterin https://purl.org/becyt/ford/1.6 https://purl.org/becyt/ford/1 |
| Sumario: | Pterins are normal components of cells and they have been previously identified as good photosensitizers under UV-A irradiation, inducing DNA damage and oxidation of nucleotides. In this work, we have investigated the ability of pterin (Ptr), the parent compound of oxidized pterins, to photosensitize the oxidation of another class of biomolecules, aminoacids, using tryptophan (Trp) as a model compound. Irradiation of Ptr in the UV-A spectral range (350 nm) in aerated aqueous solutions containing Trp led to the consumption of the latter, whereas the Ptr concentration remained unchanged. Concomitantly, hydrogen peroxide (H2O2) was produced. Although Ptr is a singlet oxygen (1O2) sensitizer, the degradation of Trp was inhibited in O2-saturated solutions, indicating that a 1O2-mediated process (Type II oxidation) was not an important pathway leading to Trp oxidation. By combining different analytical techniques, we could establish that a Type I photooxidation was the prevailing mechanism, initiated by an electron transfer from the Trp molecule to the Ptr triplet excited state yielding the corresponding radical ions (Trp.+/Trp(-H). and Ptr.-). The Trp reaction products that could be identified by UPLC-mass spectrometry are in agreement with this conclusion. |
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