Mitochondria, oxygen free radicals, disease and ageing

Superoxide is generated by the mitochondrial respiratory chain. The transfo rmation of this superoxide into hydrogen peroxide and, under certain condit ions, then into hydroxyl radicals is important in diseases where respirator y chain function is abnormal or where superoxide dismutase function is alte red, as in amyotrophic lateral sclerosis. In additon, these reactive oxygen species can influence the ageing process through mechanisms involving muta genesis of mtDNA or increased rates of shortening of telomeric DNA.