Posted 12 December 2005 - 06:23 PM
interesting study:
Biochem Mol Biol Int. 1995 May;35(6):1281-97. Related Articles, Links
Cu/Zn-superoxide dismutase and glutathione peroxidase during aging.
de Haan JB, Cristiano F, Iannello RC, Kola I.
Institute of Reproduction and Development, Monash University,
Clayton, Victoria, Australia.
During oxidative metabolism harmful reactive oxygen species (ROS)
are generated. These species are neutralized by antioxidant enzymes.
Firstly, superoxide dismutase (Sod) converts superoxide radicals (.O2-)
to hydrogen peroxide (H2O2). Thereafter catalase (Cat) and glutathione
peroxidase (Gpx) independently convert this to water. An imbalance in
the ratio of Sod to Gpx and Cat results in the accumulation of H2O2
which may participate in the Fenton reaction, resulting in the
formation of noxious hydroxyl radicals. These ROS are highly reactive
and cause damage to macromolecules such as DNA, protein and lipids. We
propose that it is the balance in the activity of the Sod to Gpx plus
Cat ratio (Sod/(Gpx plus Cat)) that is an important determinant of
cellular aging. This is based on our observation that an altered
Cu/Zn-superoxide dismutase (Sod1)/(Gpx1 plus Cat) ratio exists in the
brain of aging mice and that this correlates with increased lipid
damage. Conversely, aging liver and kidney have an unaffected
Sod1/(Gpx1 plus Cat) ratio and lipid damage is not increased with
aging. We also examine the Sod1 to Gpx1 ratio in Down syndrome tissue
and show that all organs have an altered ratio. This may contribute to
the premature aging seen in these individuals. We show that binding of
a p50/p65 complex to an NF-kappa B consensus sequence is enhanced by
H2O2 treatment in NIH3T3 cells. Thus an altered Sod1/(Gpx1 plus Cat)
ratio may also affect gene expression by altering the binding and/or
availability of transcription factors to DNA.
PMID: 7492966 [PubMed - indexed for MEDLINE]