ABSTRACT
This chapter presents the hypothesis that proteolytic systems may have an important role in overall antioxidant defenses. Free radicals and related oxidants have long been studied as agents of tissue damage. A proteolytic system consists of proteinases, proteases, and peptidases and can catalyze the complete degradation of proteins to free amino acids. Induction of proteolytic enzymes, in response to an immediate challenge, is also an effective method for ensuring both specificity and efficiency. The degradation of intracellular proteins is conveniently measured in mature erythrocytes, or in reticulocytes, by the formation of alanine. Mitochondria are capable of limited protein synthesis in vitro, which allows the incorporation of radiolabeled amino acids into newly synthesized protein. It is important to distinguish between a possible stimulation of proteolytic enzymes by oxidants and enhanced rates of degradation of oxidatively damaged proteins.
