Hydrogen peroxide metabolism and sensing in human erythrocytes: a validated kinetic model and reappraisal of the role of peroxiredoxin II
| Autor: | Gianluca Selvaggio, Rui Benfeitas, Armindo Salvador, Fernando Antunes, Pedro M. B. M. Coelho |
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| Rok vydání: | 2014 |
| Předmět: |
GPX1
Erythrocytes Thioredoxin reductase Biochemistry Peroxide Models Biological chemistry.chemical_compound Physiology (medical) Humans Hydrogen peroxide chemistry.chemical_classification Reactive oxygen species biology Computational Biology Hydrogen Peroxide Peroxiredoxins Catalase Kinetics Oxidative Stress chemistry biology.protein Thioredoxin Oxidation-Reduction NADP Peroxidase Signal Transduction |
| Zdroj: | Free radical biologymedicine. 74 |
| ISSN: | 1873-4596 |
| Popis: | Hydrogen peroxide (H 2 O 2 ) metabolism in human erythrocytes has been thoroughly investigated, but unclear points persist. By integrating the available data into a mathematical model that accurately represents the current understanding and comparing computational predictions to observations we sought to (a) identify inconsistencies in present knowledge, (b) propose resolutions, and (c) examine their functional implications. The systematic confrontation of computational predictions with experimental observations of the responses of intact erythrocytes highlighted the following important discrepancy. The high rate constant (10 7 –10 8 M −1 s −1 ) for H 2 O 2 reduction determined for purified peroxiredoxin II (Prx2) and the high abundance of this protein indicate that under physiological conditions it consumes practically all the H 2 O 2 . However, this is inconsistent with extensive evidence that Prx2’s contribution to H 2 O 2 elimination is comparable to that of catalase. Models modified such that Prx2’s effective peroxidase activity is just 10 5 M −1 s −1 agree near quantitatively with extensive experimental observations. This low effective activity is probably due to a strong but readily reversible inhibition of Prx2’s peroxidatic activity in intact cells, implying that the main role of Prx2 in human erythrocytes is not to eliminate peroxide substrates. Simulations of the responses to physiological H 2 O 2 stimuli highlight that a design combining abundant Prx2 with a low effective peroxidase activity spares NADPH while improving potential signaling properties of the Prx2/thioredoxin/thioredoxin reductase system. |
| Databáze: | OpenAIRE |
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