Activity of glutathione peroxidase and glutathione reductase in the human lens related to age.

Lenses from 42 eye bank eyes were assayed for glutathione peroxidase and glutathione reductase activities. The activity of glutathione peroxidase, when considered as a function of age, was lowest in the neonate lens, increasing with age to reach maximal values in young adult lenses, and thereafter progressively decreasing with ages greater than 40 years. Glutathione reductase activity was little affected by age when expressed as activity per lens, per gram lens or per mg soluble protein, indicating that activity of this enzyme did not increase with lens size as would a representative lenticular protein. However, the activity of this enzyme per gram lens was among the highest of any species yet examined.

Glutathione peroxidase, glutathione reductase and glutathione-S-transferase activities in the rhesus monkey lens as a function of age.

The activities of glutathione peroxidase, glutathione reductase and glutathione-S-transferase were determined in lenses from rhesus monkeys (Macaca mulatta) as a function of age. The ages ranged from 137 day old embryos to a 34 year old. Glutathione peroxidase activity (units/g lens) occurred at a very low level in lenses of fetuses and neonates, but increased dramatically with age, peaking in the adult of about 12 to 20 years of age and declining thereafter. Glutathione reductase activity (units/g lens) decreased throughout juvenile life, leveling off when adulthood was reached (at least 6 years of age). Glutathione-S-transferase activity showed considerable age-related variation. Calculations show that glutathione reductase is rate-limiting in the glutathione redox pathway.

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.