Protective Effect of Ascorbic Acid on the Breakdown of Proteins Exposed to Hydrogen Peroxide in Chicken Skeletal Muscle1
- Resource Type
- Article
- Authors
- Gecha, Oksana M.; Fagan, Julie M.
- Source
- The Journal of Nutrition; November 1992, Vol. 122 Issue: 11 p2087-2093, 7p
- Subject
- Language
- ISSN
- 00223166; 15416100
Ascorbic acid is believed to protect cells from oxidative damage by reacting with oxygen-derived free radicals. We investigated whether ascorbic acid would affect the rate of breakdown of skeletal muscle proteins in extracts exposed to hydrogen peroxide. Ascorbic acid (20 mmol/L) alone had little or no effect on the rate of ATP-independent or ATP-dependent breakdown of proteins in chicken skeletal muscle. Pretreatment of chicken skeletal muscle extracts with 10 mmol/L H2O2resulted in a complete loss of ATP-dependent proteolysis and a significant increase (14- to 15-fold) in the rate of ATP-independent protein breakdown. Ascorbic acid (20 mmol/L) did not prevent H2O2(10 mmol/L) from inactivating the ATP-dependent proteolytic pathway in skeletal muscle. However, ascorbic acid (20 mmol/L) prevented the H2O2-induced increase in the ATP-independent proteolysis of endogenous muscle proteins. Ascorbic acid also slowed the rate of hydrolysis of exogenously added [3H]superoxide dismutase exposed to H2O2and inhibited the enhanced degradation of [3H]lysozyme and H2O2-treated [3H]superoxide dismutase by the proteolytic systems exposed to H2O2. Thus ascorbic acid seems to inhibit the H2O2-induced increase in ATP-independent proteolysis 1) by preventing damage to proteins by H2O2resulting in a decreased supply of substrates for the ATP-independent degradative system and 2) by preventing activation of the proteolytic enzymes that participate in the energy-independent degradation of H2O2-treated proteins.