Species survey of glutathione peroxidase and glutathione reductase: Search for an animal model of the human lens

Lenses from representative species of eight mammalian orders were assayed for glutathione peroxidase and glutathione reductase activities. Wide variation of glutathione peroxidase activity was noted, the lowest activity being that of the prosimian galago while the highest activities were from three Old World monkey species of the genera Macaca and Papio. The hominoids, including the human, all exhibited lower activities of this enzyme. Glutathione reductase activity was lowest in the dog, the rabbit, and all species of cats. The higher Old World monkeys and hominoids, including the human, exhibited enzyme activities many times greater than any other species except the woodchuck. Since glutathione reductase is the rate-controlling enzyme of the glutathione redox cycle, it may be concluded that the most suitable model for the human lenticular glutathione redox cycle will only be found among the higher primates.