Unique increase of superoxide dismutase level in brains of long living mammals.

A possible involvement of superoxide dismutase (SOD) level in determination of mammal's lifespan was examined by comparing six different enzyme levels including SOD in brains of eleven mammalian species of different lifespans. When the specific activities of the enzymes were plotted against lifespans on a linear scale, no or weak negative correlations were observed for all enzymes studied except SOD, which revealed positive correlation. The uniqueness of the SOD level suggests that it is one of the enzymes which evolved together with lifespans. It would contribute to long lifespan through protection against oxygen toxicity.