EFFECTS OF LASER IRRADIATION OF SELF- ASSEMBLED COMPLEXES OF PHOTOSENSITIZERS WITH GLOBULAR PROTEINS

Abstract

Photosensitization of proteins is a critical phenomenon observed in biological systems and extensively utilized in experimental research. This process involves interactions between photosensitizers light-sensitive molecules and proteins, leading to structural and functional changes. In this study, we aimed to create and analyze artificial photoreceptor protein models using various metalloporphyrins as photosensitizers. Specifically, we investigated complexes formed between zinc protoporphyrin IX (ZnPPIX), tin protoporphyrin IX (SnPPIX), manganese protoporphyrin IX (MnPPIX), magnesium protoporphyrin IX (MgPPIX), protoporphyrin IX (PPIX), and hemin protoporphyrin IX (HeminPPIX) with two globular proteins: bovine beta-lactoglobulin (BLG) and human serum albumin (HSA). These complexes were subjected to laser irradiation to simulate photochemical reactions. We employed UV-Vis absorption spectroscopy, fluorescence emission, lifetime decay measurements, and circular dichroism (CD) spectroscopy to monitor interactions and light-induced modifications. Our results reveal that the type of metalloporphyrin, environmental pH, and specific protein influence the extent and nature of these modifications. Different metalloporphyrins caused varying degrees of structural changes in BLG and HSA, with distinct patterns based on pH conditions. This study highlights the complex interplay between photosensitizers, proteins, and environmental factors in photochemical processes. These findings are valuable for optimizing artificial photoreceptor models for applications in photodynamic therapy, molecular imaging, and fields where controlled light-induced protein modifications are essential.