Implications of protein degradation in aging.

Aging is characterized by accumulation of potentially harmful altered proteins that could lead to gradual deterioration of cellular functions and eventually result in increased probability of death. Metabolic turnover of proteins thus plays an essential role in maintaining the life of an organism. In this article we summarize our current knowledge on age-related changes in protein turnover with special reference to degradation. Increase in half-life of proteins with advancing age is well documented. Qualitative rather than quantitative changes of proteasomes appear to be responsible for this change. Dietary restriction and moderate long-term exercise seem to restore higher proteasome activity and turnover rate of proteins in aged animals.