The effect of age on corneal and lens superoxide dismutase

The enzymatic activity of copper-zinc superoxide dismutase within the cornea and lens of the juvenile (1 week) and adult (26 week) rat has been measured relative to both total soluble protein and immunoreactive protein. Enzymatic activity of corneal superoxide dismutase, localized in the epithelium and endothelium, remains constant with age relative to total soluble protein and the ratio of catalytically active enzyme to immunoreactive enzyme is near unity indicating that the superoxide dismutase present is enzymatically active. Likewise, in the juvenile rat, the majority of lens superoxide dismutase, which is located in the capsule epithelium, is enzymatically active. However, in the adult rat a large portion of the enzyme present is catalytically inactive. The enzymatic activity also decreases relative to total soluble protein with age in both the rat and the rabbit lens. This decrease in protection against toxic radicals and/or the accumulation of enzymatically defective enzyme may be contributing factors to age related lens disorders.