PHOTOINDUCED DAMAGE TO PROTEOLIPOSOMES BY A LIPOPHILIC PHOTOSENSITIZER

CARLOS ARDILA; M. LAURA DÁNTOLA; VANESA HERLAX; MARIANA VIGNONI

Congreso; 47 th Annual meeting of the Brazilian Biophysic society; 2023

Many natural heterocyclic compounds such as pterins, flavins, porphyrins can act as photosensitizers (Sens), molecules that absorb UV/visible radiation and produce chemical changes in another biomolecule, such as lipids, DNA and proteins (1). In proteins, these processes can lead to protein oxidation, oligomerization, fragmentation, and covalent adduct formation (2,3). Photosensitization of lipids results in peroxidation and increased membrane permeability (4,5). Since the reactions that occur in solution are not necessarily replicated in vivo, the main objective of this work is to investigate the chemical, functional, and structural changes that occur in proteins and membrane lipids due to photoinduced processes using proteoliposomes (PLs) as a biomimetic model. In this case, to create the PLs, we use large unilamelar vesicles (LUVs) of phospholipids with unsaturated fatty acid formed by the extrusion method and, Tyrosinase (TYR), an enzyme that catalyzes the first and rate-limiting step in the biosynthesis of the melanin. A lipophilic sensitizer will be added to PLs to obtain photoproteoliposomes (PPL). The Sens used was 3-decyl-riboflavin (decyl-Rf), which was previously synthesized, characterized, and evaluated as a Sens capable of binding to lipid membranes. Photolysis experiments were performed at pH 7,4 with visible light (445 nm). Protein damage is assessed by measuring TYR enzymatic activity with a spectrophotometric technique, by measure the generation of dopachroma (475 nm).This work was supported by Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT-Grants PICT 2019-3416 and 2020-3103), Universidad Nacional de La Plata (UNLP-Grant X840) and Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, PUE 2017-22920170100100CO).References1) Baptista, M., et. al. Photochem. Photobiol., 2017, 93, 912-919.2) Reid O., et. al. Biochemistry, 2020, 59, 44, 4213.3) Dántola L., et. al. Chem. Res. Toxicol., 2019, 32, 2250-2259.4) Vignoni A., et. al. Dyes Pigm., 2021,187, 109131, 1-10.5) Bacellar I., et.al. JACS, 2018, 140, 30, 9606-9615.