scholarly journals The plastoquinone pool outside the thylakoid membrane serves in plant photoprotection as a reservoir of singlet oxygen scavengers

2018 ◽  
Vol 41 (10) ◽  
pp. 2277-2287 ◽  
Author(s):  
Brigitte Ksas ◽  
Bertrand Légeret ◽  
Ursula Ferretti ◽  
Anne Chevalier ◽  
Pavel Pospíšil ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Thylakoid Membrane ◽  
Oxygen Scavengers ◽  
Plastoquinone Pool

scholarly journals Chlororespiration

2000 ◽  
Vol 355 (1402) ◽  
pp. 1541-1547 ◽  
Author(s):  
Peter J. Nixon
Keyword(s):  
Electron Transfer ◽  
Thylakoid Membrane ◽  
Redox State ◽  
Original Model ◽  
Current Status ◽  
Electrochemical Gradient ◽  
Electron Transfer Chain ◽  
Plastoquinone Pool ◽  
Transfer Chain ◽  
Photosynthetic Electron Transfer

The term ‘chlororespiration’ is used to describe the activity of a putative respiratory electron transfer chain within the thylakoid membrane of chloroplasts and was originally proposed by Bennoun in 1982 to explain effects on the redox state of the plastoquinone pool in green algae in the absence of photosynthetic electron transfer. In his original model, Bennoun suggested that the plastoquinone pool could be reduced through the action of a NAD(P)H dehydrogenase and could be oxidized by oxygen at an oxidase. At the same time an electrochemical gradient would be generated across the thylakoid membrane. This review describes the current status of the chlororespiration model in light of the recent discoveries of novel respiratory components within the chloroplast thylakoid membrane.

Singlet oxygen scavengers affect laser-dye impairment of endothelium-dependent responses of brain arterioles

1996 ◽  
Vol 270 (4) ◽  
pp. H1258-H1263 ◽  
Author(s):  
W. I. Rosenblum ◽  
G. H. Nelson
Keyword(s):  
Singlet Oxygen ◽  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Protective Effects ◽  
Laser Dye ◽  
Oxygen Scavengers ◽  
Heat Injury

This study investigates the possible role of singlet oxygen in accounting for the inhibitory effect of laser-dye injury on endothelium-dependent dilations. The combination of helium-neon (HeNe) laser (20-s exposure) and intravascular Evans blue impairs endothelium-dependent dilation of mouse pial arterioles by acetylcholine (ACh), bradykinin (BK), and calcium ionophore A23187. Each has a different endothelium-derived mediator (EDRFACh, EDRFBK, EDRFionophore, respectively). In this study, diameters at a craniotomy site were monitored in vivo with an image splitter-television microscope. The laser-dye injury, as usual, abolished the responses 10 and 30 min after injury, with recovery, complete or partial, at 60 min. Dilations by sodium nitroprusside, an endothelium-independent dilator, were not affected by laser-dye. When the singlet oxygen scavengers L-histidine (10(-3) M) and L-tryptophan (10(-2) M) were added to the suffusate over the site, the responses to ACh at 10 and 30 min were relatively intact, the response to BK was partly protected at 10 min only, and the response to ionophore was still totally impaired at 10 and 30 min. Lysine, a nonscavenging amino acid, had no protective effects with any dilator. We postulate that a heat-induced injury initiates a chain of events resulting in prolonged singlet oxygen generation by the endothelial cell (not by the dye). We postulate further that destruction of EDRFACh by singlet oxygen is responsible for laser-dye inhibition of ACh and that generation of the radical must continue for > or = 30 min. On the other hand, the heat injury itself is probably responsible for the elimination of the response to ionophore. Heat plus singlet oxygen generated by heat-damaged tissue may initially impair the response to BK, but by 30 min only the effects of some other factor, presumably heat injury, account for the impaired response to BK.

Improved Functional Recovery of Ischemic Rat Hearts due to Singlet Oxygen Scavengers Histidine and Carnosine

1999 ◽  
Vol 31 (1) ◽  
pp. 113-121 ◽  
Author(s):  
John W. Lee ◽  
Hiroshi Miyawaki ◽  
Elizabeth V. Bobst ◽  
Jeff D. Hester ◽  
Muhammad Ashraf ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Functional Recovery ◽  
Oxygen Scavengers ◽  
Rat Hearts

Free radicals and singlet oxygen scavengers: Reaction of a peroxy-radical with β-carotene, diphenyl furan and 1,4-diazobicyclo(2,2,2)-octane

1981 ◽  
Vol 98 (4) ◽  
pp. 901-906 ◽  
Author(s):  
J.E. Packer ◽  
J.S. Mahood ◽  
V.O. Mora-Arellano ◽  
T.F. Slater ◽  
R.L. Willson ◽  
...  
Keyword(s):  
Free Radicals ◽  
Singlet Oxygen ◽  
Peroxy Radical ◽  
Oxygen Scavengers ◽  
Β Carotene

Colorimetric Determination of Singlet Oxygen Scavengers Using a Protein Photosensitizer

2020 ◽  
Vol 14 (2) ◽  
pp. 148-157
Author(s):  
Miso Kim ◽  
Eun Hye Kim ◽  
Thi Hai Yen Pham ◽  
Tuan Anh Hoang Le ◽  
Thi Phuong Do ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Colorimetric Determination ◽  
Oxygen Scavengers

Interconversion of Carotenoids and Quinones after Onset of Photosynthesis in Chloroplasts of Higher Plants

1983 ◽  
Vol 38 (5-6) ◽  
pp. 393-398 ◽  
Author(s):  
K. H. Grumbach
Keyword(s):  
Electron Transport ◽  
Thylakoid Membrane ◽  
Redox State ◽  
Higher Plants ◽  
Enzyme System ◽  
Photosynthetic Electron Transport ◽  
Dark Light ◽  
Plastoquinone Pool ◽  
Violaxanthin Deepoxidase ◽  
Spinach Leaves

The interconversion of carotenoids and quinones was investigated in beech and spinach leaves as well as isolated intact spinach chloroplasts following a dark-light transition. It is shown that isolated intact chloroplasts which are preincubated for 2 h at pH 7.6 in the dark and re­illuminated with strong white light are capable not only of deepoxidizing violaxanthin into antheraxanthin and zeaxanthin but simultaneously change the redox state of the plastoquinone- pool in their thylakoid membrane. At the same time as violaxanthin is deepoxidized plastohydroquinone-9 is oxidized to plastoquinone-9. If the light is turned off zeaxanthin is epoxidized into antheraxanthin and violaxanthin but no significant change in the redox state of the plastoquinone-pool occurred. It is concluded that the deepoxidation of violaxanthin is connected to the photosynthetic electron transport in that way that an acidification of the intrathylakoidal compartment by the vectorial release of protons from the water photooxidizing enzyme system and the plastoquinone- pool is required for the activation of the violaxanthin deepoxidase. This may be taken as further evidence that violaxanthin deepoxidase is located at the inner side of the thylakoid membrane. Additional evidence for this location site is given by the observation that neither deepoxidation of violaxanthin nor photooxidation of plastohydroquinone-9 occurred after onset of photosyn­thesis if non cyclic electron transport was inhibited by DCMU.

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