Changes during aging in rat lens endopeptidase activity.
Protein degradation has been implicated in lens aging and cataract development. We propose that proteolytic enzymes are important in these processes. In this study, lens neutral proteinase activity and thermal stability have been measured as a function of cell age and animal age in rat lens. Epithelial, cortical, and nuclear lens regions from animals between 1 and 25 months were analyzed. Specific activity and thermal stability were found to decrease with lens cell age, that is, from epithelium to nucleus. Specific activity in the cortex increased with animal age, while specific activity in the nuclear region remained constant with animal age. In the epithelium, specific activity showed no correlation with animal age. In 15 day old rats, thermal stability curves for the cortical enzyme were linear, indicating only one form of activity hydrolyzing synthetic substrate was present. At 1.25 months of age, thermal stability curves for the cortical enzyme were non-linear indicating that multiple forms of the activity were present.
D000375:Aging; D000818:Animals; D002454:Cell Differentiation; D010450:Endopeptidases / Q000378:metabolism*; D007908:Lens, Crystalline / Q000166:cytology / Q000201:enzymology*; D008666:Metalloendopeptidases; D008667:Metalloproteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D008667:Metalloproteins; D010450:Endopeptidases; D008666:Metalloendopeptidases