Protoplasma

, Volume 205, Issue 1, pp 29–36

Plasmalemma-associated malate dehydrogenase activity in onion root cells

  • M. C. Córdoba-Pedregosa
  • J. A. González-Reyes
  • A. Serrano
  • J. M. Villalba
  • P. Navas
  • F. Córdoba
Article

DOI: 10.1007/BF01279290

Cite this article as:
Córdoba-Pedregosa, M.C., González-Reyes, J.A., Serrano, A. et al. Protoplasma (1998) 205: 29. doi:10.1007/BF01279290

Summary

Plasma membrane vesicles isolated from onion roots showed oxaloacetate reductase activity as well as other oxidoreductase activities. Purification and further sequencing showed that the protein responsible for the activity is a 40 kDa protein which corresponds to the cytosolic soluble malate dehydrogenase. However, the activity remained bound to the membrane after repeated freezing and thawing cycles and further washing, excluding a cytosolic contamination as the source of the activity. Furthermore, a second 28 kDa protein has been copurified together with the 40 kDa protein. The plasmalemma oxaloacetate reductase activity shows both donor and acceptor sites located towards the cytoplasmic side of the plasma membrane. This enzyme catalyzed the oxidation of NADH by oxaloacetate and the reduction of NAD+ by malate in the presence of an oxaloacetate-withdrawing system. We conclude that a significant amount of the cytosolic malate dehydrogenase can be specifically attached to the cytosolic face of the plasmalemma. A possible role in a putative malate shuttle associated to the plasma membrane is discussed.

Keywords

Allium cepa L.Malate dehydrogenaserootPlasma membrane

Abbreviations

AFR

ascorbate free radical

DQ

duroquinone

OA

oxaloacetate

DPIP

dichlorophenolindophenol

MDH

malate dehydrogenase

PHMB

p-hydroxymercuribenzoate

Copyright information

© Springer-Verlag 1998

Authors and Affiliations

  • M. C. Córdoba-Pedregosa
    • 1
  • J. A. González-Reyes
    • 1
  • A. Serrano
    • 1
  • J. M. Villalba
    • 1
  • P. Navas
    • 2
  • F. Córdoba
    • 3
  1. 1.Departamento de Biología Celular, Facultad de CienciasUniversidad de CórdobaCórdobaSpain
  2. 2.Departamento de Economía y EmpresaUniversidad “Pablo de Olavide”Sevilla
  3. 3.Departamento de Ciencias AgroforestalesUniversidad de HuelvaHuelva