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NAD(P)H-ubiquinone oxidoreductases in plant mitochondria

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Author

Summary, in English

Plant (and fungal) mitochondria contain multiple NAD(P)H dehydrogenases in the inner membrane all of which are connected to the respiratory chain via ubiquinone. On the outer surface, facing the intermembrane space and the cytoplasm, NADH and NADPH are oxidized by what is probably a single low-molecular-weight, nonproton-pumping, unspecific rotenone-insensitive NAD(P)H dehydrogenase. Exogenous NADH oxidation is completely dependent on the presence of free Ca2+ with a K0.5 of about 1 μM. On the inner surface facing the matrix there are two dehydrogenases: (1) the proton-pumping rotenone-sensitive multisubunit Complex I with properties similar to those of Complex I in mammalian and fungal mitochondria. (2) a rotenone-insensitive NAD(P)H dehydrogenase with equal activity with NADH and NADPH and no proton-pumping activity. The NADPH-oxidizing activity of this enzyme is completely dependent on Ca2+ with a K0.5 of 3 μM. The enzyme consists of a single subunit of 26 kDa and has a native size of 76 kDa, which means that it may form a trimer.

Publishing year

1993-08

Language

English

Pages

377-384

Publication/Series

Journal of Bioenergetics and Biomembranes

Volume

25

Issue

4

Document type

Journal article

Publisher

Springer

Topic

  • Biochemistry and Molecular Biology

Keywords

  • (Plant) mitochondria
  • calcium
  • Complex I
  • electrostatic interactions
  • NAD(P)H dehydrogenase
  • NAD(P)H-ubiquinone oxidoreductase
  • rotenone

Status

Published

Research group

  • Plant Biology

ISBN/ISSN/Other

  • ISSN: 0145-479X