Iron release analyses from ferritin by visible light irradiation

Area of Science:

• Biochemistry
• Photochemistry
• Molecular Biology

Background:

• Ferritin is the primary intracellular iron-storage protein.
• Iron release from ferritin is crucial for cellular iron homeostasis but its regulation is not fully understood.
• Previous studies suggest light can influence iron release, but mechanisms remain unclear.

Purpose of the Study:

• To investigate the direct effect of visible light irradiation on iron release from ferritin.
• To determine the role of adenosine diphosphate (ADP) in light-induced iron release.
• To elucidate the conditions and factors influencing this process.

Main Methods:

• Ferritin solutions were irradiated with white fluorescent light (17,000 lx).
• Iron release was measured under varying conditions, including pH, presence/absence of ADP, temperature, and oxygen levels.
• The effect of irradiation dose and light cessation/re-initiation was monitored.

Main Results:

• Light irradiation slightly induced iron release from ferritin at acidic pH (5.0-6.0) without ADP.
• ADP markedly enhanced light-induced iron release under the same acidic conditions.
• Iron release was dependent on irradiation dose and acidity, but not temperature, oxygen, or free radicals; release ceased upon light removal and resumed upon re-irradiation.

Conclusions:

• Visible light directly induces iron release from ferritin.
• The process involves the photoreduction of iron stored within the ferritin molecule.
• Adenosine diphosphate (ADP) significantly potentiates light-induced iron release, particularly under acidic conditions.