Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9604478 | Journal of Biotechnology | 2005 | 8 Pages |
Abstract
Yeast (Saccharomyces cerevisiae) mutants lacking cytoplasmic superoxide dismutase (CuZnSOD) show Lys and Met auxotrophy under aerobic conditions. This metabolic defect can be ameliorated by exogenous ascorbate as well as other antioxidants (glutathione, cysteine and N-acetylcysteine). Restoration of growth of CuZnSODâ yeast mutants on media devoid of Met and/or Lys may therefore be a simple and useful means to detect and quantify antioxidants. The protective effect of antioxidants is oxygen-dependent: the lower the oxygen content of the atmosphere, the lower antioxidant concentrations are required to restore prototrophy. Therefore, the sensitivity of the test can be augmented by growing the yeast under lowered partial oxygen pressure. While 6Â mM, 10Â mM and 30Â mM ascorbate was necessary to restore the growth in the absence of Met, in the absence of Lys, and in the absence of Lys and Met, respectively, under 21% oxygen, 3Â mM and 6Â mM ascorbate was sufficient for growth restoration in the absence of Lys and in the absence of Lys and Met, respectively, under 3% oxygen. The protective effects of cysteine and N-acetylcysteine peaked at 0.5Â mM and 6Â mM, respectively, disappearing at higher concentrations of these compounds, pointing to the detection of not only protective but also toxic cellular effects of the compounds studied by the test proposed.
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Physical Sciences and Engineering
Chemical Engineering
Bioengineering
Authors
Ewa Å»yracka, Renata ZadrÄ
g, Sabina KozioÅ, Anna KrzepiÅko, Grzegorz Bartosz, Tomasz BiliÅski,