Protoplasma

, Volume 205, Issue 1, pp 107–113

Ubiquinol regeneration by plasma membrane ubiquinone reductase

  • A. Arroyo
  • F. Navarro
  • P. Navas
  • J. M. Villalba
Article

DOI: 10.1007/BF01279300

Cite this article as:
Arroyo, A., Navarro, F., Navas, P. et al. Protoplasma (1998) 205: 107. doi:10.1007/BF01279300

Summary

Several enzyme systems have been proposed to play a role in the maintenance of ubiquinol in membranes other than the inner mitochondrial membrane. The aim of this study was to investigate the mechanisms involved in NADH-driven regeneration of antioxidant ubiquinol at the plasma membrane. Regeneration was measured by quantifying the oxidized and reduced forms of ubiquinone by electrochemical detection after separation by high-performance liquid chromatography. Plasma membrane incubation with NADH resulted in the consumption of endogenous ubiquinone, and a parallel increase in ubiquinol levels. The activity showed saturation kinetics with respect to the pyridine nucleotides and was moderately inhibited byp-hydroxymercuribenzoate. Only a slight inhibition was achieved with dicumarol at concentrations reported to fully inhibit DT-diaphorase. Salt-extracted membranes displayed full activity of endogenous ubiquinol regeneration, supporting the participation of an integral membrane protein. In liposomes-reconstituted systems, the purified cytochromeb5 reductase catalyzed the reduction of the natural ubiquinone homologue coenzyme Q10 at rates accounting for the activities observed in whole plasma membranes, and decreased the levels of lipid peroxidation. Our data demonstrate the role of the cytochromeb5 reductase in the regeneration of endogenous ubiquinol.

Keywords

Antioxidant protectionDT-diaphoraseCytochromeb5 reductasePlasma membraneα-TocopherolUbiquinone

Abbreviations

AAPH

2,2′-azobis-(2-amidinopropane) hydrochloride

CoQ

coenzyme Q, ubiquinone

CoQH2

reduced coenzyme Q, ubiquinol

pHMB

p-hydroxymercuribenzoate

Copyright information

© Springer-Verlag 1998

Authors and Affiliations

  • A. Arroyo
    • 1
  • F. Navarro
    • 1
  • P. Navas
    • 1
  • J. M. Villalba
    • 1
  1. 1.Departamento de Biologfa Celular, Facultad de CienciasUniversidad de CórdobaCórdobaSpain
  2. 2.Departamento de Economía y Empresa, Facultad de Ciencias ExperimentalesUniversidad “Pablo de Olavide”SevillaSpain