Rates of vectorial proton transport supported by cyclic electron flow during oxygen reduction by illuminated intact chloroplasts

1994 ◽  
Vol 41 (3) ◽  
pp. 419-428 ◽  
Author(s):  
Yoshichika Kobayashi ◽  
Ulrich Heber
Keyword(s):  
Oxygen Reduction ◽  
Proton Transport ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Intact Chloroplasts

Isolation and Properties of Functional Mesophyll Protoplasts and Chloroplasts From Zea mays

1981 ◽  
Vol 8 (1) ◽  
pp. 21 ◽  
Author(s):  
DA Day ◽  
CLD Jenkins ◽  
MD Hatch
Keyword(s):  
Zea Mays ◽  
Oxygen Evolution ◽  
Pyridoxal Phosphate ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
The Other ◽  
Mesophyll Protoplasts ◽  
Intact Chloroplasts ◽  
Common Carrier ◽  
High Concentrations

A procedure is described for the preparation of metabolically active mesophyll protoplasts from maize, and of functional, intact chloroplasts from these protoplasts. Intact protoplasts show no oxygen evolution with 3-phosphoglycerate or with oxalacetate plus pyruvate as substrates, even when these substances are provided at high concentrations. On the other hand, protoplast extracts and chloroplasts display rates of oxygen evolution of 2-3 �mol min-1 (mg Chl)-1 with the same substances. Pyruvate stimulates oxalacetate-dependent oxygen evolution substantially, indicating good coupling between non-cyclic electron flow and phosphorylation. Low PI concentrations stimulate 3-phosphoglycerate-dependent oxygen evolution; high PI concentrations, and pyridoxal phosphate, inhibit this activity, suggesting a common carrier for 3-phosphoglycerate and PI.

On the Role of Plastoquinone in Photosynthesis

1971 ◽  
Vol 26 (4) ◽  
pp. 341-352 ◽  
Author(s):  
H. Böhme ◽  
S. Reimer ◽  
A. Trebst
Keyword(s):  
Photosystem Ii ◽  
Electron Transport Chain ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Cyclic System ◽  
Transport Chain ◽  
Cyclic Photophosphorylation ◽  
Intact Chloroplasts ◽  
Flow Through

Dibromothymoquinone and its hydroquinone are inhibitors of non cyclic electron flow from water to NADP, anthraquinone or methylviologen. The inhibition is competetively reversed by plastoquinone. It appears that dibromothymoquinone is an antagonist of plastoquinone and that it prevents the enzymic (by the next endogenous carrier of the chloroplast electron transport chain) but not the chemical (by ferricyanide) reoxidation of reduced plastoquinone. This follows from the result that the photoreduction of ferricyanide and DCPIP * is not inhibited by dibromothymoquinone in sonicated chloroplasts and is inhibited in intact chloroplasts to only 60% or 80% respectively. It is concluded that dibromothymoquinone does not inhibit photoreductions by photosystem II.According to their response to dibromothymoquinone, cyclic photophosphorylations can be subdivided in those requiring plastoquinone and those which do not. Menadione catalyzed cyclic photophosphorylation is inhibited by dibromothymoquinone, whereas the PMS catalyzed system is not. The DAD cyclic system is only partly inhibited by dibromothymoquinone. The PMS catalyzed cyclic photophosphorylation in the presence of dibromothymoquinone is antimycin sensitive, which suggests that the PMS system can switch from a plastoquinone dependent system to a plastoquinone independent, but cytochrome b dependent system, which is now antimycin sensitive. Ferredoxin catalyzed cyclic photophosphorylation is inhibited by dibromothymoquinone as well as by antimycin. The data indicate that non cyclic electron flow through both photosystems is obligatory dependent on plastoquinone, whereas cyclic systems do not necessarily include plastoquinone. The relevance of the results to the possibility of different coupling sites in cyclic and non cyclic electron flow systems is discussed.

scholarly journals Cyclic Electron Flow within PSII Functions in Intact Chloroplasts from Spinach Leaves

2002 ◽  
Vol 43 (8) ◽  
pp. 951-957 ◽  
Author(s):  
Chikahiro Miyake ◽  
Kuniaki Yonekura ◽  
Yoshichika Kobayashi ◽  
Akiho Yokota
Keyword(s):  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Intact Chloroplasts ◽  
Spinach Leaves

Protonmotive cyclic electron flow around photosystem I in intact chloroplasts

FEBS Letters ◽  
1979 ◽  
Vol 98 (2) ◽  
pp. 386-390 ◽  
Author(s):  
David Crowther ◽  
John D. Mills ◽  
Geoffrey Hind
Keyword(s):  
Photosystem I ◽  
Electron Flow ◽  
Cyclic Electron Flow ◽  
Intact Chloroplasts

Physiological Role of Cyclic Electron Flow in Higher Plants

2012 ◽  
Vol 30 (1) ◽  
pp. 100
Author(s):  
Wei HUANG ◽  
Shi-Bao ZHANG ◽  
Kun-Fang CAO
Keyword(s):  
Higher Plants ◽  
Electron Flow ◽  
Physiological Role ◽  
Cyclic Electron Flow
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