Optical and kinetic properties of semireduced plastoquinone and ubiquinone: Electron acceptors in photosynthesis

Bensasson, René V.; Land, Edward J.

doi:10.1016/0005-2728(73)90163-1

Cited by 131 publications

(29 citation statements)

References 14 publications

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“…Contrary to the changes measured in the UV [14], the spectrum of Qa-is considerably distorted in the blue region as compared to the plastosemiquinone anion spectrum obtained in vitro in [15]. This may be due, particularly the 430 nm trough, to a local electrochromic effect of the semiquinone on PS80.…”

Section: Acceptor Sidecontrasting

confidence: 64%

Absorption changes of Photosystem II donors and acceptors in algal cells

Lavergne

1984

FEBS Letters

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Flash‐induced absorption changes were measured in the 390–450 nm region, using whole cells of a double mutant strain of Chlorella sorokiniana, lacking PS I centers and part of the pigment antenna. Spectral changes associated with PS II acceptors (Qa and Qb) and donors (p680, Z and L) are described. In this region, the spectrum obtained for Qb −/Qb differs markedly from that of Qa −/Qa. Different spectra were also obtained for the secondary donor (Z+/Z) when measured after one or three flashes.

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Section: Acceptor Sidecontrasting

confidence: 64%

Absorption changes of Photosystem II donors and acceptors in algal cells

Lavergne

1984

FEBS Letters

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“…This light rninus dark difference spectrum shown by the solid line in Fig. 2 (Van Gorkom, 1974) shows good agreement with that observed by Bensasson and Land (1973) for the plastosemiquinone anion minus fully oxidized plastoquinone difference spectrum (the dashed line in Fig. 2).…”

Section: A Chemical Identitysupporting

confidence: 73%

The Primary Reaction of Plant Photosystem Ii

Knaff

1977

Photochem & Photobiology

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Abstract-Research during the past five years has resulted in considerable advances in our understanding of the primary reaction (the initial light-induced charge separation) of plant Photosystem I1 (the reaction responsible for the oxidation of H 2 0 to 02). The primary reaction appears to involve the photooxidation of a specialized chlorophyll Q and the concomitant photoreduction of a specialized plastoquinone. Evidence for this formulation of the Photosystem I1 reaction center and a discussion of the kinetic and oxidation-reduction properties of the reactants are reviewed.

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“…Although the absorption changes observed in the 430 nm region were similar in both cases, indicating that the (P 700 ϩ -P 700 ) spectrum was not affected by the mutations, they were significantly different in the 300 -360 nm region. In particular, a pronounced absorption increase peaking at ϳ320 nm was specifically observed in the mutant, consistent with the expected absorption changes associated with plastoquinone reduction (37). Taken together, these data indicate that, as in Synechocystis sp.…”

supporting

confidence: 74%

“…The pigments were extracted as described (37), sequentially with 1 ml of methanol, 1 ml of 1:1 (v/v) methanol/acetone, and 1 ml of acetone, and the three extracts were combined, and the resulting solution was concentrated by vacuum. The pigments were resuspended in a mixture of 1:1 methanol/isopropyl alcohol at 0.77 mg of Chl ml Ϫ1 .…”

mentioning

confidence: 99%

Loss of Phylloquinone in Chlamydomonas Affects Plastoquinone Pool Size and Photosystem II Synthesis

Lefebvre-Legendre

Rappaport

Finazzi

et al. 2007

Journal of Biological Chemistry

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Phylloquinone functions as the electron transfer cofactor at the A 1 site of photosystem I. We have isolated and characterized a mutant of Chlamydomonas reinhardtii, menD1, that is deficient in MenD, which encodes 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase, an enzyme that catalyzes the first specific step of the phylloquinone biosynthetic pathway. The mutant is photosynthetically active but light-sensitive. Analysis of total pigments by mass spectrometry reveals that phylloquinone is absent in menD1, but plastoquinone levels are not affected. This is further confirmed by the rescue of menD1 by addition of phylloquinone to the growth medium. Analysis of electron transfer by absorption spectroscopy indicates that plastoquinone replaces phylloquinone in photosystem I and that electron transfer from A 1 to the iron-sulfur centers is slowed down at least 40-fold. Consistent with a replacement of phylloquinone by plastoquinone, the size of the free plastoquinone pool of menD1 is reduced by 20 -30%. In contrast to cyanobacterial MenD-deficient mutants, photosystem I accumulates normally in menD1, whereas the level of photosystem II declines. This decrease is because of reduced synthesis of the photosystem II core subunits. The relationship between plastoquinone occupancy of the A 1 site in photosystem I and the reduced accumulation of photosystem II is discussed.

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Optical and kinetic properties of semireduced plastoquinone and ubiquinone: Electron acceptors in photosynthesis

Cited by 131 publications

References 14 publications

Absorption changes of Photosystem II donors and acceptors in algal cells

Absorption changes of Photosystem II donors and acceptors in algal cells

The Primary Reaction of Plant Photosystem Ii

Loss of Phylloquinone in Chlamydomonas Affects Plastoquinone Pool Size and Photosystem II Synthesis

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