Superoxide production by cytochrome b559. Mechanism of cytosol-independent activation

Vasilij Koshkin*, Edgar Pick

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

69 Scopus citations


Purified cytochrome b559 relipidated with either a mixture of phosphatidylcholine and phosphatidic acid or with phosphatidylcholine only exhibits high and low superoxide (O2) producing ability, respectively, in the absence of cytosolic activators [Koshkin, V. and Pick, E. (1993) FEBS Lett. 327, 57-62]. This system was used as a model for the study of the mechanism of NADPH oxidase activation. It is shown that, depending on the composition of the phospholipid environment, cytochrome b559 binds FAD with high or low affinity, this being accompanied by changes in flavin absorbance and fluorescence. High affinity binding of FAD to cytochrome b559 relipidated with phosphatidylcholine combined with phosphatidic acid is associated with an enhanced NADPH-driven O2- producing capacity. A kinetic study of O2- production by cytochrome b559 reflavinated under stoichiometric FAD binding conditions revealed an FAD/heme ratio of 1:2. A further kinetic study of O2 production by high- and low-activity relipidated and reflavinated eytochrome b559, at varying substrate concentrations, and the determination of steady-state difference spectra of such preparations, reduced by NADPH, indicated that O2- production is activated by facilitation of electron transfer from NADPH to FAD rather than by an enhancement of NADPH binding.

Original languageEnglish
Pages (from-to)285-289
Number of pages5
JournalFEBS Letters
Issue number3
StatePublished - 7 Feb 1994


  • Cytochrome b
  • FAD
  • NADPH oxidase
  • Phospholipid
  • Superoxide


Dive into the research topics of 'Superoxide production by cytochrome b559. Mechanism of cytosol-independent activation'. Together they form a unique fingerprint.

Cite this