Ceruloplasmin enhances DNA damage induced by hydrogen peroxide in vitro

Abstract

Ceruloplasmin (Cp) was found to promote the oxidative damage to DNA, as evidenced by the formation of 8-hydroxy-2′-deoxyguanosine and strand breaks, when incubated with H₂O₂ in vitro. The capacity of Cp to enhance oxidative damage to DNA was inhibited by hydroxyl radical scavengers such as sodium azide and mannitol, a metal chelator, diethylenetriaminepenta-acetic acid, and catalase. Although the oxidized protein resulted in an increase in the content of carbonyl groups, the ferroxidase activity and the proteolytic susceptibility were not significantly altered. The release of a portion of Cu from Cp was observed, and conformational alterations were indicated by the changes in fluorescence spectra. Based on these results, we suggest that damage to DNA is mediated in the H₂O₂/Cp system via the generation of ^·OH by released Cu²⁺ and/or loosely bound Cu exposed from oxidatively damaged Cp through the conformational change. The release of Cu from Cp during oxidative stress could enhance the formation of reactive oxygen species and could also potentiate cellular damage.

Keywords:

• Ceruloplasmin
• reactive oxygen species
• DNA damage
• conformational change