Studies on the pathway of cyclic electron flow in mesophyll chloroplasts of a C4 plant

Steven C Huber, G. E. Edwards

Research output: Contribution to journalArticle

Abstract

1. Cyclic photophosphorylation driven by white light, as followed by 14CO2 fixation by mesophyll chloroplast preparations of the C4 plant Digitaria sanguinalis, was specifically inhibited by disalicylidenepropanediamine (DSPD), antimycin A, 2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone (DBMIb), 1-ethyl-3(3-dimethylaminopropyl)-carbodiimide (EDAC), and KCN suggesting that ferredoxin, cytochrome b563, plastoquinone, cytochrome f, and plastocyanin are obligatory intermediates of cyclic electron flow. It was found that 0.2 μM DCMU and 40 μM o-phenanthroline blocked noncyclic electron flow, stimulated cyclic photophosphorylation, and caused a partial reversal (40-100%) of the inhibition by DBMIB and antimycin A, but not DSPD. 2. Cyclic photophosphorylation could also be activated using only far-red illumination. Under this condition, however, cyclic photophosphorylation was much less sensitive to the inhibitors DBMIB, EDAC and antimycin A, but remained completely sensitive to DSPD and KCN. Inhibition in far-red light was not increased by preincubating the chloroplasts with the various inhibitors for several minutes in white light. 3. The striking correspondence between the effects of photosystem II inhibitors, DCMU and o-phenanthroline, on cyclic photophosphorylation under white light and cyclic photophosphorylation under far-red light (in the absence of photosystem II inhibitors) suggests that electrons flowing from photosystem II may regulate the pathway of cyclic electron flow.

Original languageEnglish (US)
Pages (from-to)420-433
Number of pages14
JournalBBA - Bioenergetics
Volume449
Issue number3
DOIs
StatePublished - Dec 6 1976

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Photophosphorylation
Chloroplasts
Electrons
Antimycin A
Photosystem II Protein Complex
Light
Ethyldimethylaminopropyl Carbodiimide
Diuron
Dibromothymoquinone
Digitaria
Cytochromes f
Plastocyanin
Plastoquinone
Plant Preparations
Ferredoxins
Lighting

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

Cite this

Studies on the pathway of cyclic electron flow in mesophyll chloroplasts of a C4 plant. / Huber, Steven C; Edwards, G. E.

In: BBA - Bioenergetics, Vol. 449, No. 3, 06.12.1976, p. 420-433.

Research output: Contribution to journalArticle

Huber, Steven C ; Edwards, G. E. / Studies on the pathway of cyclic electron flow in mesophyll chloroplasts of a C4 plant. In: BBA - Bioenergetics. 1976 ; Vol. 449, No. 3. pp. 420-433.
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