A chloroplast absorbance change from violaxanthin de-epoxidation. A possible component of 515 nm changes

Yamamoto, Harry Y.; Wang, Yuqing; Kamite, Lavonne

doi:10.1016/0006-291x(71)90358-5

Cited by 18 publications

(7 citation statements)

References 9 publications

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“…The activity of 8-HQS, as an inhibitor of microorganisms producing pectolytic enzymes, may be similar to that of tannin or rufianic acid (12,17). 8-HQS was included in the "Ottawa" solution for these reasons and for its reported effects on closure of stomata, prevention of xylem blockage, and metal-chelating properties (7, 22,24,40,42). The pH of the aqueous solutions of 50 ppm of 8-HQS, or the 100 ppm of Na-isoAA was 3.9 and 6.0, respectively, and helped to maintain the acidity of the "Ottawa" solution near a level beneficial for water uptake by rose stems.…”

Section: Resultsmentioning

confidence: 99%

Extension of Vase-Life of Cut Flowers by Use of Isoascorbate - Containing Preservative Solutions1,2

Parups¹,

Chan²

1973

J. Amer. Soc. Hort. Sci.

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Section: Resultsmentioning

confidence: 99%

Extension of Vase-Life of Cut Flowers by Use of Isoascorbate - Containing Preservative Solutions1,2

Parups¹,

Chan²

1973

J. Amer. Soc. Hort. Sci.

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“…Evidence has been cited that the epoxide cycle plays a role in protecting the chloroplast against lethal photosensitized oxidations (21,22), that it is involved in photosynthetic oxygen evolution (23), photosynthetic oxygen uptake (24), is inhibited by inhibitors of photosynthetic phosphorylation (3), and operates only at high light intensities under conditions where CO2 incorporation becomes limiting (25). The cycle has also been implicated in the 515-nm change that occurs when photosynthetic systems are illuminated (2,26).…”

Section: Discussionmentioning

confidence: 99%

Carotenoid Transformations in the Chloroplast Envelope

Jeffrey

Douce²,

Benson³

1974

Proc. Natl. Acad. Sci. U.S.A.

100

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The envelope of the spinach chloroplast is a yellow membrane system with a unique carotenoid composition. Envelopes prepared from dark-treated leaves had a violaxanthin content up to 3.5 times the lutein plus zeaxanthin content, whereas in chloroplast envelopes from illuminated leaves this ratio was only 0.75. Light-catalyzed changes in violaxanthin content also occurred in the thylakoid fraction.The role of this reversible light-catalyzed de-epoxidation of violaxanthin in the function of the envelope of the chloroplast is discussed.In a recent paper by Douce et al. (1) it was reported that violaxanthin constituted a greater proportion of the carotenoids of the chloroplast envelope than of the thylakoids of ordinarily prepared spinach chloroplasts. There is now considerable evidence (2) that the conversion of violaxanthin to zeaxanthin occurs when isolated spinach chloroplasts are illuminated. The biochemical mechanism of this conversion has been studied (3, 4), but its physiological significance remains obscure (2).In this paper we report the recognition of a light-dependent conversion of violaxanthin to zeaxanthin in the envelope of spinach chloroplasts. MATERIALS AND METHODSSpinach obtained from local markets was stored briefly at 40. Whole leaves were washed, placed in water at 20°, and exposed either to white light (1.2 X 108 ergs/cm2 per sec) or to darkness for 2 hr. Chloroplasts were prepared according to the "aqueous" method of Walker (5). The purification of intact chloroplasts-(class I) was carried out by a modification of the method of Leech (6). The chloroplast envelope, thylakoid, and stroma were prepared and characterized as described (1). The membrane fractions isolated by discontinuous sucrose gradient centrifugation were concentrated as pellets by centrifugation.Protein content was determined by the method of Lowry et al. (7)

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“…This component, which is strictly dependent on the energization of the thylakoids by acidification of the luminal compartment [10, 359, 360, 366, 369, 370], is characterised by relatively rapid relaxation kinetics when the actinic illumination is turned off (in the order of ~1-2 min). Acidification of the lumen is responsible for at least two factors determining the onset of qE: 1) it activates the thylakoid-bound violaxanthin de-epoxidase enzyme (VDE), a crucial enzyme of the so-called xanthophyll cycle [287, 360, 371, 372], able to convert violaxanthin to zeaxanthin [372]; 2) it activates the PsbS protein by protonation of two lumen-exposed glutamate residues [373]. PsbS is a particular product of the Lhc gene superfamily with four transmembrane helices that is necessary for fast (tens of seconds to a few minutes) qE activation [374], even though slow qE formation in the absence of PsbS has been more recently reported (about half an hour) [375].…”

Section: Photoinhibition Regulation Of Light Harvesting Capacity Andmentioning

confidence: 99%

A Comparison Between Plant Photosystem I and Photosystem II Architecture and Functioning

Caffarri

Tibiletti²,

Jennings³

et al. 2014

CPPS

215

158

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Oxygenic photosynthesis is indispensable both for the development and maintenance of life on earth by converting light energy into chemical energy and by producing molecular oxygen and consuming carbon dioxide. This latter process has been responsible for reducing the CO2 from its very high levels in the primitive atmosphere to the present low levels and thus reducing global temperatures to levels conducive to the development of life. Photosystem I and photosystem II are the two multi-protein complexes that contain the pigments necessary to harvest photons and use light energy to catalyse the primary photosynthetic endergonic reactions producing high energy compounds. Both photosystems are highly organised membrane supercomplexes composed of a core complex, containing the reaction centre where electron transport is initiated, and of a peripheral antenna system, which is important for light harvesting and photosynthetic activity regulation. If on the one hand both the chemical reactions catalysed by the two photosystems and their detailed structure are different, on the other hand they share many similarities. In this review we discuss and compare various aspects of the organisation, functioning and regulation of plant photosystems by comparing them for similarities and differences as obtained by structural, biochemical and spectroscopic investigations.

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A chloroplast absorbance change from violaxanthin de-epoxidation. A possible component of 515 nm changes

Cited by 18 publications

References 9 publications

Extension of Vase-Life of Cut Flowers by Use of Isoascorbate - Containing Preservative Solutions1,2

Extension of Vase-Life of Cut Flowers by Use of Isoascorbate - Containing Preservative Solutions1,2

Carotenoid Transformations in the Chloroplast Envelope

A Comparison Between Plant Photosystem I and Photosystem II Architecture and Functioning

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