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Methylene Blue Location in (Hydroperoxized) Cardiolipin Monolayer: Implication in Membrane Photodegradation
R M de Souza1, P Siani1, T F Schmidt2
1Departamento de Química, FFCLRP, Universidade de São Paulo , Avenida Bandeirantes 3900, 14040-901, Ribeirão Preto, SP, Brazil.
The Journal of Physical Chemistry. B
|August 19, 2017
Summary
Methylene blue photoexcitation initiates cardiolipin oxidation via singlet oxygen attack. The excited dye
Area of Science:
- Biochemistry
- Physical Chemistry
- Membrane Biophysics
Background:
- Phospholipid oxidation is crucial in biological systems.
- Methylene blue (MB) is a photosensitizer.
- Cardiolipin (CL) is a key mitochondrial phospholipid.
Purpose of the Study:
- Investigate initial phospholipid oxidation steps.
- Elucidate the role of methylene blue photoexcitation.
- Understand cardiolipin oxidation mechanisms.
Main Methods:
- Molecular dynamics simulations.
- Simulations of cardiolipin (CL) and cardiolipin hydroperoxide (CLOOH) monolayers.
- Consideration of MB electronic states (singlet and triplet).
Main Results:
- CL photooxidation initiated by MB likely follows a Type II mechanism.
- Singlet oxygen attacks CL unsaturations, forming lipid hydroperoxide.
- Hydroperoxide group localizes at the aqueous interface, altering membrane properties.
- MB shifts from parallel to normal orientation upon excitation, favoring Type I oxidation.
- Hydrogen atom transfer from hydroperoxide to excited MB observed.
Conclusions:
- MB photoexcitation drives CL oxidation through distinct mechanisms.
- Oxidation leads to altered membrane structure and potential photodamage.
- Findings advance understanding of lipid oxidation in biomembranes.