Mitochondrial matrix proteins are sensitive to oxidative inactivation, and oxidized proteins are known to accumu-late during ageing. The Lon protease is believed to play an important role in the degradation of oxidized matrix pro-teins such as oxidized aconitase. We reported previously that an age-related accumulation of altered proteins occurs in the liver matrix of rats and that the ATP-stimulated proteolytic activity, referred as to Lon-like protease activ-ity, decreases considerably in 27 month-old rats, whereas no concomitant changes in the levels of Lon protein expression occur in the liver
