Charge compensation during the phagocyte respiratory burst
| Autor: | Thomas E. DeCoursey, Ricardo Murphy |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Proton channel
Voltage-gated proton channel Neutrophils Biophysics Biochemistry Cell membrane 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Superoxides medicine Animals Humans Respiratory Burst 030304 developmental biology Phagosome Phagocytes 0303 health sciences Oxidase test NADPH oxidase biology pH Chemistry Superoxide Cell Membrane NADPH Oxidases Depolarization Cell Biology Electron current Respiratory burst Cell biology Kinetics medicine.anatomical_structure Phagocyte biology.protein Reactive Oxygen Species 030217 neurology & neurosurgery |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Bioenergetics. 1757(8):996-1011 |
| ISSN: | 0005-2728 |
| DOI: | 10.1016/j.bbabio.2006.01.005 |
| Popis: | The phagocyte NADPH oxidase produces superoxide anion (O(2)(.-)) by the electrogenic process of moving electrons across the cell membrane. This charge translocation must be compensated to prevent self-inhibition by extreme membrane depolarization. Examination of the mechanisms of charge compensation reveals that these mechanisms perform several other vital functions beyond simply supporting oxidase activity. Voltage-gated proton channels compensate most of the charge translocated by the phagocyte NADPH oxidase in human neutrophils and eosinophils. Quantitative modeling of NADPH oxidase in the plasma membrane supports this conclusion and shows that if any other conductance is present, it must be miniscule. In addition to charge compensation, proton flux from the cytoplasm into the phagosome (a) helps prevent large pH excursions both in the cytoplasm and in the phagosome, (b) minimizes osmotic disturbances, and (c) provides essential substrate protons for the conversion of O(2)(*-) to H(2)O(2) and then to HOCl. A small contribution by K+ or Cl- fluxes may offset the acidity of granule contents to keep the phagosome pH near neutral, facilitating release of bactericidal enzymes. In summary, the mechanisms used by phagocytes for charge compensation during the respiratory burst would still be essential to phagocyte function, even if NADPH oxidase were not electrogenic. |
| Databáze: | OpenAIRE |
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