title: Enhancement of glutathione-dependent haemin degradation by ascorbic acid.
abstract: In the current work, we investigated the effect of ascorbic acid on GSH-mediated haemin degradation. GSH-mediated haemin degradation in the presence of ascorbic acid in phosphate-buffered saline and in erythrocyte ghosts was determined by recording absorbance at 365 and 399nm, respectively. Generation of intracellular H(2)O(2) was measured indirectly in terms of the inactivation of endogenous catalase in erythrocytes in the presence of 3-amino-1,2,4-triazole. Although ascorbic acid itself did not induce haemin degradation, it enhanced GSH-mediated haemin degradation. Experiments with catalase showed that H(2)O(2) was essential in this process. The oxidation of ascorbic acid in the presence of haemin was stimulated by GSH, suggesting that ascorbic acid can alter the mechanism of H(2)O(2) generation observed with GSH and haemin alone. These results suggest that enhancement of GSH-mediated haemin degradation by ascorbic acid may be due to an increase in the production of H(2)O(2) generated by GSH and haemin in the absence of ascorbic acid.
authors.affiliation: School of Biological Biomedical and Molecular Sciences, University of New England, Armidale, NSW 2351, Australia.
authors.forename: Cheng-Gang
authors.initials: CG
authors.lastname: Zou
authors.forename: Nihal S
authors.initials: NS
authors.lastname: Agar
authors.forename: Graham Lloyd
authors.initials: GL
authors.lastname: Jones
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001205:Ascorbic Acid / Q000494:pharmacology*; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism*; D006427:Hemin / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007501:Iron / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012756:Sheep
chemical_list: D000975:Antioxidants; D017382:Reactive Oxygen Species; D006427:Hemin; D006861:Hydrogen Peroxide; D007501:Iron; D005978:Glutathione; D001205:Ascorbic Acid