Proteolysis, caloric restriction and aging.

The nature of the aging process has been the subject of considerable speculation. It is believed that free radical damage to cellular components is one of the main contributors to the aging process. Studies on proteins have shown age-related decline in enzyme activities, age-related accumulation of oxidized proteins and a decline of the proteolytic machinery of the cell. The proteasome, a highly regulated intracellular proteolytic system, is the major enzymatic system responsible for the degradation of damaged proteins. The current knowledge on regulation and of the properties of this unique proteolytic system with special emphasis to the aging process are discussed in this review. Since it is known that caloric restriction (CR) is the only method to delay the aging process and extend the maximal lifespan the effects of CR on the age-related decline in protein degradation is highlighted.