Superoxide radical formation by pure complex I (NADH:ubiquinone oxidoreductase) from Yarrowia lipolytica. Academic Article uri icon

Overview

abstract

  • Generation of reactive oxygen species (ROS) is increasingly recognized as an important cellular process involved in numerous physiological and pathophysiological processes. Complex I (NADH:ubiquinone oxidoreductase) is considered as one of the major sources of ROS within mitochondria. Yet, the exact site and mechanism of superoxide production by this large membrane-bound multiprotein complex has remained controversial. Here we show that isolated complex I from Yarrowia lipolytica forms superoxide at a rate of 0.15% of the rate measured for catalytic turnover. Superoxide production is not inhibited by ubiquinone analogous inhibitors. Because mutant complex I lacking a detectable iron-sulfur cluster N2 exhibited the same rate of ROS production, this terminal redox center could be excluded as a source of electrons. From the effect of different ubiquinone derivatives and pH on this side reaction of complex I we concluded that oxygen accepts electrons from FMNH2 or FMN semiquinone either directly or via more hydrophilic ubiquinone derivatives.

publication date

  • June 28, 2005

Research

keywords

  • Electron Transport Complex I
  • Superoxides
  • Yarrowia

Identity

Scopus Document Identifier

  • 24044471810

Digital Object Identifier (DOI)

  • 10.1074/jbc.M504709200

PubMed ID

  • 15985426

Additional Document Info

volume

  • 280

issue

  • 34