Photoptosis mechanism: Hydrogen Peroxide–Induced Formation of an Endogenous Porphyrin Photosensitizer from Cytochrome c

Abstract

The study investigates the mechanism of photoptosis, focusing on the role of cytochrome c-derived porphyrin as an endogenous photosensitizer in mitochondrial membrane oxidation. The research explores the process of heme destruction induced by hydrogen peroxide and its subsequent photodynamic effects. The research employed spectrophotometric methods to evaluate heme destruction in cytochrome c. The study measured porphyrin degradation by monitoring the Soret band optical density reduction and detected iron release using xylenol orange. Lipid peroxidation was assessed through chemiluminescence and TBA-reactive product formation under 441 nm laser irradiation.
The study demonstrated that a tenfold excess of hydrogen peroxide leads to approximately 80% porphyrin destruction in cytochrome c, accompanied by iron release. The porphyrin residue of cytochrome c was identified as an active endogenous photosensitizer. Under laser irradiation, this photosensitizer significantly enhanced lipid peroxidation processes.
Photosensitizer from cytochrome c drives mitochondrial membrane oxidation through photodynamic action, providing new insights into the mechanisms of cell death and potential applications in photodynamic therapy. The findings highlight the dual role of cytochrome c in both apoptotic and photodynamic cell death pathways.

Speaker

German O. Stepanov
N.I. Pirogov Russian National Research Medical University, Dpt. of General and Medical biophysics, Medical biological faculty
Russia

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