Oxidants - Impact of Aging

Human cells become physiologically compromised with advancing age. Among the contributing processes are DNA damage and inefficient DNA repair mechanisms, the shortening of chromosome ends (known as “telomeres”), non-enzymatic modification of intracellular proteins, and the accumulation of various ROS. Two organelles are the primary source of the excess ROS — the mitochondrion and the peroxisome.

Mitochondria have long been known to produce ROS as byproducts of energy metabolism. Research by Drs. Terlecky and Walton showed peroxisomes of aged cells, through their inability to efficiently import catalase, also produced ROS. Although import of the hydrogen peroxide-producing oxidases was also impaired in the older cells, it was catalase that was the most dramatically affected by the aging process. With the balance of peroxisomal pro- and antioxidants upset, the affected cells produced excess hydrogen peroxide. This and other research has led to the suggestion that the peroxisome and its antioxidant enzyme catalase are important factors in the aging process.