Superoxide dismutase: correlation with life-span and specific metabolic rate in primate species.

Much evidence now suggests that superoxide dismutase (superoxide:superoxide oxidoreductase, EC 1.15.1.1) may be a major intracellular protective enzyme against oxygen toxicity by catalyzing the removal of the superoxide radical. We examined the possible role this enzyme may have in determining the life-span of primate species. Superoxide dismutase specific activity levels were measured in cytoplasmic fractions of liver, brain, and heart of 2 rodent and 12 primate species. These species had maximum life-span potentials ranging from 3.5 to 95 years. Liver, brain, and heart had similar specific activity levels for a given species, but the levels for different species varied over 2-fold, with man having the highest level. No general correlation was found in the levels with life-span. However, the ratio of superoxide dismutase specific activity to specific metabolic rate of the tissue or of the whole adult organism was found to increase with increasing maximum lifespan potential for all the species. This correlation suggests that longer-lived species have a higher degree of protection against by-products of oxygen metabolism.

Superoxide dismutase, thermal respiratory acclimation, and growth in an earthworm, Eisenia foetida.

The superoxide dismutase activity units/mg protein were determined for earthworms (Eisenia foetida) acclimated at 15°, 22.5° and 30°C. Worms acclimated at 15° gave a value of SOD units significantly lower than those acclimated at 30°. Those at 22.5° gave an intermediate value. SOD activity units of the anterior, mid and posterior regions showed no indication of the classical U-shaped axial gradient of respiration. SOD levels increased as O2uptake increased, though to a lesser extent, indicating that SOD levels are somehow tied to metabolic rate even if not in a one to one relationship. The increased ratio of SOD/specific metabolic rate of 15° compared to 30° acclimates implies that at 15° worms have more protection against the superoxide radical and thus would be expected to survive longer.