Oxidative Stress Induces Impairment of Human Erythrocyte Energy Metabolism through the Oxygen Radical-mediated Direct Activation of AMP-deaminase
| Autor: | Tavazzi, B, Amorini, A. M., Fazzina, G, DI PIERRO, D, Tuttobene, M, Giardina, B, Lazzarino, Giuseppe, Amorini, ANGELA MARIA |
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| Předmět: |
Hydroxyl radicals
Erythrocytes Radical Lipid peroxidation Iodoacetates Red blood cells medicine.disease_cause Hemolysis Biochemistry AMP Deaminase Enzyme activator G-6-PDH deficiency medicine Energy Metabolism Oxidative stress ROS Hemoglobin Humans Protein Structure Quaternary Molecular Biology Incubation chemistry.chemical_classification Reactive oxygen species AMP deaminase Cell Biology Enzyme Activation Oxidative Stress Red blood cell Enzyme medicine.anatomical_structure chemistry Ethylmaleimide Hydroxymercuribenzoates Reactive Oxygen Species |
| Zdroj: | Scopus-Elsevier Europe PubMed Central |
| Popis: | The effect of oxidative stress on human red blood cell AMP-deaminase activity was studied by incubating either fresh erythrocytes or hemolysates with H(2)O(2) (0.5, 1, 2, 4, 6, 8, and 10 mm) or NaNO(2) (1, 5, 10, 20, and 50 mm), for 15 min at 37 degrees C. AMP-deaminase tremendously increased by increasing H(2)O(2) or NaNO(2) at up to 4 and 20 mm, respectively (maximal effect for both oxidants was 9.5 and 6.5 times higher enzymatic activity than control erythrocytes or hemolysates, respectively). The incubation of hemolysates with iodoacetate (5-100 mm), N-ethylmaleimide (0.1-10 mm), or p-hydroxymercuribenzoate (0.1-5 mm) mimicked the effect of oxidative stress on AMP-deaminase, indicating that sulfhydryl group modification is involved in the enzyme activation. In comparison with control hemolysates, changes of the kinetic properties of AMP-deaminase (decrease of AMP concentration necessary for half-maximal activation, increase of V(max), modification of the curve shape of V(o) versus [S], Hill plots, and coefficients) were recorded with 4 mm H(2)O(2)- and 1 mm N-ethylmaleimide-treated hemolysates. Data obtained using 90% purified enzyme, incubated with Fenton reagents (Fe(2+) + H(2)O(2)) or -SH-modifying compounds, demonstrated that (i) reactive oxygen species are directly responsible for AMP-deaminase activation; (ii) this phenomenon occurs through sulfhydryl group modification; and (iii) the activation does not involve the loss of the tetrameric protein structure. Results of experiments conducted with glucose-6-phosphate dehydrogenase-deficient erythrocytes, challenged with increasing doses of the anti-malarial drug quinine hydrochloride and showing dramatic AMP-deaminase activation, suggest relevant physiopathological implications of this enzymatic activation in conditions of increased oxidative stress. To the best of our knowledge, this is the first example of an enzyme, fundamental for the maintenance of the correct red blood cell energy metabolism, that is activated (rather than inhibited) by the interaction with reactive oxygen species. |
| Databáze: | OpenAIRE |
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