title: Protective effect of ascorbic acid on the breakdown of proteins exposed to hydrogen peroxide in chicken skeletal muscle.
abstract: 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 H2O2 resulted 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 H2O2 and 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 H2O2 resulting 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.
authors.affiliation: Department of Animal Sciences, Rutgers University, New Brunswick, NJ 08903.
authors.forename: O M
authors.initials: OM
authors.lastname: Gecha
authors.forename: J M
authors.initials: JM
authors.lastname: Fagan
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000494:pharmacology*; D002645:Chickens; D010450:Endopeptidases / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006868:Hydrolysis / Q000187:drug effects; D008297:Male; D009113:Muramidase / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010084:Oxidation-Reduction; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D009124:Muscle Proteins; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase; D009113:Muramidase; D010450:Endopeptidases; D001205:Ascorbic Acid