Oxidation-reduction coupled phosphorylation in the dark with isolated spinach chloroplasts

Bruce R. Selman, Donald R. Ort

Research output: Contribution to journalArticle

Abstract

1. Spinach chloroplasts, pre-incubated with ferricyanide, acquire the ability to make ATP in the dark provided they are supplied with a reductant and a lipophilic mediator that can penetrate the membrane. The mediator must be of the type that, upon oxidation, releases protons into the surrounding medium such as 2,3,5,6-tetramethyl-p-phenylenediamine (DAD). 2. Dark phosphorylation is not affected by the electron transport inhibitor, 3(3,4-dichlorophenyl)-1,1-dimethyl urea (DCMU) or 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIB), but is inhibited by uncouplers of photophosphorylation (e.g. NH4Cl and carbonylcyanide-m-chlorophenylhydrazone (CCCP)) and high concentrations of the energy transfer inhibitor, Dio-9. 3. Because only catalytic amounts of the mediator DAD are required to saturate dark phosphorylation, it is concluded that DAD shuttles reducing equivalents across the membrane from the reductant, ascorbate, on the outside, to ferricyanide, the oxidant, trapped on the inside. 4. The results are interpreted within the framework of the chemiosmotic hypothesis for the coupling of electron transport to phosphorylation.

Original languageEnglish (US)
Pages (from-to)101-112
Number of pages12
JournalBBA - Bioenergetics
Volume460
Issue number1
DOIs
StatePublished - Apr 11 1977
Externally publishedYes

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Phosphorylation
Spinacia oleracea
Chloroplasts
Oxidation-Reduction
Reducing Agents
Electron Transport
Dibromothymoquinone
Photophosphorylation
Membranes
Energy Transfer
Oxidants
Energy transfer
Urea
Protons
Adenosine Triphosphate
Oxidation
hexacyanoferrate III

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

Cite this

Oxidation-reduction coupled phosphorylation in the dark with isolated spinach chloroplasts. / Selman, Bruce R.; Ort, Donald R.

In: BBA - Bioenergetics, Vol. 460, No. 1, 11.04.1977, p. 101-112.

Research output: Contribution to journalArticle

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