Chemical, structural and functional modifications of proteins phototriggered by an endogenous photosensitizer

REID, LARA O.; LHIAUBET-VALLET, VIRGINIE; HERLAX, VANESA; LORENTE, CAROLINA; THOMAS, ANDRÉS H.; DANTOLA, MARIA LAURA

Alburqueque

Congreso; American Society for Photobiology-2022 Biennial Meeting; 2022

American Society for Photobiology

Electromagnetic radiation is able to modify the chemical structure of many biomolecules. Most of the solar UV energy incident on Earth surface corresponds to UV-A radiation, which is not absorbed significantly by the components of the biological systems, but acts indirectly through photosensitized reactions. These reactions are key players both on beneficial and harmful processes triggered by UV and visible light. Epidemiological evidence has shown that exposure of humans to artificial UV-A radiation, is a major risk factor for melanoma induction. On the other hand, photosensitization can be used to treat different types of cancer by photodynamic therapy and is also important due to several applications in disinfection and photodynamic inactivation of microorganisms.Pterins, a family of heterocyclic compounds, are widespread in living systems and participate in important biological functions. In pathological conditions, such as vitiligo, oxidized pterins accumulate in the white skin patches of patients suffering this depigmentation disorder. These molecules present a profuse and amazing photochemistry and are endogenous photosensitizer that act via type I (electron transfer) or type II (singlet oxygen), or a combination of both mechanism. Proteins are one of the preferential targets of the photosensitized damaging effects of UV radiation on biological system. In general, it is accepted that the photosensitization of proteins occurs mainly through the reactions of singlet oxygen with different amino acid residues. Nevertheless, it has been demonstrated that pterins photosensitize peptides, proteins and their components mainly through a type I mechanism. In the context of our investigations on the photosensitizing properties of pterins, an overview of the photosensitization damage of different kind of proteins by pterin derivatives will be presented, focusing the attention on the chemical modifications of tyrosine and tryptophan residues and its effect on protein structure and function.