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Simultaneous Measurement of Superoxide/Hydrogen Peroxide and NADH Production by Flavin-containing Mitochondrial Dehydrogenases

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Mechanisms involved in A2E oxidation.

So Ra Kim¹, Steffen Jockusch, Yasuhiro Itagaki

¹Department of Ophthalmology, Columbia University, 630 W.168th Street, NY 10032, USA.

Experimental Eye Research

|April 29, 2008

Summary

This summary is machine-generated.

Irradiation of A2E, a lipofuscin pigment, generates superoxide anions and hydroxyl radicals. However, superoxide anions do not directly oxidize A2E but can further oxidize its already-oxidized forms.

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Light-driven Enzymatic Decarboxylation

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Published on: May 22, 2016

Area of Science:

Biochemistry
Ophthalmology
Photochemistry

Background:

A2E is a bis-retinoid pyridinium compound accumulating as lipofuscin in retinal pigment epithelial (RPE) cells.
A2E accumulation is linked to aging and inherited retinal degenerations.

Purpose of the Study:

To investigate the reactive oxygen species (ROS) generated by A2E irradiation.
To determine the role of superoxide anion in A2E oxidation.

Main Methods:

Electron paramagnetic resonance (EPR) spectroscopy with spin trapping (DMPO).
Dihydroethidium (HEt) fluorescence and luminol-based chemiluminescence assays.
High-performance liquid chromatography (HPLC) and FAB-mass spectroscopy.
Incubation with superoxide anion generators (xanthine/xanthine oxidase) and singlet oxygen generators.

Main Results:

430nm irradiation of A2E generated hydroxyl radicals (OH) and superoxide anions (O2•−).
Superoxide dismutase inhibited ROS formation, confirming superoxide generation.
Superoxide anion did not directly oxidize A2E in cell-free systems.
Peroxy-A2E, an oxidized A2E form, underwent further oxidation by superoxide anion.

Conclusions:

A2E irradiation generates ROS, including superoxide anions and hydroxyl radicals.
Superoxide anions are not involved in the initial oxidation of A2E.
Superoxide anions can contribute to the further oxidation of pre-oxidized A2E, potentially exacerbating RPE damage.