The O2- generating oxidoreductase of human neutrophils: Evidence of an obligatory requirement for calcium and magnesium for expression of catalytic activity

Terrence R. Green, David E. Wu, Mary K. Wirtz

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NADPH-dependent O2- generating oxidoreductase activity recovered from cell lysates of phorbol myristate acetate-stimulated human neutrophils exhibits dependence on Ca+2 and Mg+2 for full expression of its catalytic activity. O2- generating activity was completely abolished by exposure of the oxidoreductase to EDTA, then reconstituted by exposure of the enzyme to Ca+2 and Mg+2 in excess of the EDTA concentration used to block catalytic activity. The oxidoreductase responded maximally to either 0.25 mM Ca+2 or 0.80 mM Mg+2. The pH optimum of the oxidoreductase exposed to Ca+2 and Mg+2 is between pH 7.0 and 7.6. The molar ratio of NADPH oxidation to O2- production determined at pH 7.6 in the presence of Ca+2 and Mg+2 is 0.49, indicating 1 mole of NADPH oxidized per 2 moles of O2- formed. Particulate fractions recovered from cell lysates of resting neutrophils exhibited no oxidoreductase activity under the same conditions.

Original languageEnglish (US)
Pages (from-to)973-978
Number of pages6
JournalBiochemical and Biophysical Research Communications
Issue number3
StatePublished - Feb 10 1983


ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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