Picosecond absorbance difference spectroscopy on the primary reactions and the antenna-excited states in Photosystem I particles

Nuijs, Antonius M.; Шувалов, В.А.; Gorkom, Hans J. van; Plijter, Johan J.; Duysens, L.N.M.

doi:10.1016/0005-2728(86)90186-6

Cited by 135 publications

(96 citation statements)

References 19 publications

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“…Other Chl and phaeophytin species also produce absorbance changes in the near IR that are very similar to I'-700. These include Chl singlets and triplets, P-680, Ao, and phaeophytin (Doring et al, 1967;Klimov aet al, 1986;Nuijs et al, 1986aNuijs et al, , 1986b. However, most of these species are very short-lived (lO-" to l O w 7 s; Kramer and Mathis, 1980;Nuijs et al, 1986a;Shuvalov et al, 1986;Mathis et al, 1988;Schatz et al, 1988;Genty et al, 1992) and will not contribute to the absorbance change procluced by I'-700+, which has a lifetime of 10-3 to lO-'s (Haehnel, 1984) at the irradiances of up to 2000 to 3000 pmol m-'s-l used in whole-leaf photosynthesis experiments.…”

Section: P-700 In Leavesmentioning

confidence: 99%

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Harbinson

Hedley

1993

Plant Physiol.

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Following dark adaptation, the response to irradiance of chlorophyll (Chl) fluorescence, the light-induced absorbance change around 820 nm (to measure reaction center Chl of photosystem I[PSI] P-700 oxidation), and COz fixation were examined in pea (Pisum sativum 1.) leaves under a range of conditions. Initially, P-700 oxidation is restricted by a lack of regeneration of PSI electron acceptors, and the increase of oxidized P-700 (P-700+) that occurs during approximately the first 60 s of irradiation is largely independent of the resistance to electron flow between the two photosystems. Under these conditions, the quantum efficiency for linear electron flow is directly positively related to P-700+ accumulation, which is in contrast to the direct negative correlation that is the most frequently reported relationship between P-700+ accumulation and the quantum efficiency for linear electron flow.

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Section: P-700 In Leavesmentioning

confidence: 99%

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Harbinson

Hedley

1993

Plant Physiol.

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“…(9) and Wasielewski et al (10) have shown that PSI preparations enriched in P700 (1 P700 per 40 Chl molecules) undergo primary charge separation in about 14 ps. Nuijs et al (11,12) have suggested that electron transfer from P680 to pheophytin a (Pheoa) in PSII preparations enriched in P680 (1 P680 per 80 Chl) occurs in <35 ps. Schatz et al (13), using a preparation containing 1 P680 per 80 Chl from Synechococcus, have estimated that the electron transfer from Pheoa -to a subsequent quinone electron acceptor takes place in 510 ps.…”

mentioning

confidence: 99%

Determination of the primary charge separation rate in isolated photosystem II reaction centers with 500-fs time resolution

Wasielewski

Johnson

Seibert³

1989

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

182

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We have measured directly the rate of formation of the oxidized chlorophyll a electron donor (P680') and the reduced electron acceptor pheophytin a-(Pheoa-) following excitation of isolated spinach photosystem II reaction centers at 40C. The reaction-center complex consists of DI, D2, and cytochrome b-559 proteins and was prepared by a procedure that stabilizes the protein complex. Transient absorption difference spectra were measured from 440 to 850 nm as a function of time with 500-fs resolution following 610-nm laser excitation. The formation of P680'-Pheoa-is indicated by the appearance of a band due to P680' at 820 nm and corresponding absorbance changes at 505 and 540 nm due to formation of PheoaC. The appearance of the 820-nm band is monoexponential with T = 3.0 -0.6 ps. The time constant for decay of l*P680, the lowest excited singlet state of P680, monitored at 650 nm, is T = 2.6 _ 0.6 ps and agrees with that of the appearance of P680+ within experimental error. Treatment of the photosystem H reaction centers with sodium dithionite and methyl viologen followed by exposure to laser excitation, conditions known to result in accumulation of Pheoa-, results in formation of a transient absorption spectrum due to '*P680. We find no evidence for an electron acceptor that precedes the formation of Pheoa-.The primary processes of photosynthesis commence with light absorption by antenna pigment-protein complexes (1), followed by exciton migration among the pigments (2). Trapping of the excitons by chlorophyll a (Chla) or bacteriochlorophyll molecules in the reaction center (RC) is followed by primary charge separation, which converts the excitation energy into chemical potential (3). In isolated RC preparations from purple photosynthetic bacteria, primary charge separation occurs in about 3 ps (4-8 (25) reported that the P680+-Pheoa-lifetime depends on the number of antenna Chla molecules attached to the PSII RC. Okamura et al. (26) showed that recombination of the P680+-Pheoa-radical pair in the PSII RC complex leads to formation of the triplet state of P680. This triplet possesses the spin polarization characteristic of a radical-pair precursor. Unfortunately, the PSII RC as isolated by Nanba and Satoh is rather unstable (27) and thus no data on the kinetics of the formation of P680+-Pheoa-have appeared as yet.In this paper we report the direct measurement of the kinetics of the primary charge separation in stabilized (27, (27,28) of the original Nanba and Satoh procedure (14). All steps were carried out at 4°C in the dark. PSII membranes (30 mg of Chl at a concentration of 1 mg/ml) were solubilized in 4% (wt/vol) Triton X-100/50 mM Tris HCI, pH 7.2, for 1 hr with stirring. The material was then centrifuged for 1 hr at 100,000 x g, and the resultant supernatant was loaded onto a 15 x 1.6-cm column of Fractogel TSK DEAE-650S (EM Science, Gibbstown, NJ, but now sold by Supelco, Bellefonte, PA, under the name TSK-GEL Toyopearl DEAE-650S) preequilibrated with 50 mM Tris HCI, pH 7.2/30 mM NaCI/0.05% ...

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“…Agricultural and Food Research Council (AG 84/4). 2 Abbreviations: P-700, general term for all P-700; P-700°, reduced P-700 (this is P-700 in the zero oxidation state and is termed 'reduced' because of its relationship with P-700+); P-700+, oxidized P-700; qQ 700+) is as good a quencher of excitation energy present in PSI as is reduced P-700 (P-700°) (25), but whereas quenching by P-7000 results in electron transport from PSI, quenching by P-700+ results only in thermal deactivation of the excitation energy. Consequently, the quantum efficiency of PSI is given by the degree of reduction of the P-700 pool (i.e.…”

mentioning

confidence: 99%

Relationship between the Quantum Efficiencies of Photosystems I and II in Pea Leaves

Harbinson¹,

Genty²,

Baker³

1989

Plant Physiol.

176

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The irradiance dependence of the efficiencies of photosystems I and 11 were measured for two pea (Pisum sativum [L.]) varieties grown under cold conditions and one pea variety grown under warm conditions. The efficiencies of both photosystems declined with increasing irradiance for all plants, and the quantum efficiency of photosystem I electron transport was closely correlated with the quantum efficiency of photosystem 11 electron transport. In contrast to the consistent pattern shown by efficiency of the photosystems, the redox state of photosystem 11 (as estimated from the photochemical quenching coefficient of chlorophyll fluorescence) exhibited relationships with both irradiance and the reduction of P-700 that varied with growth environment and genotype. This variability is considered in the context of the modulation of photosystem 11 quantum efficiency by both photochemical and nonphotochemical quenching of excitation energy.The well established organization of the electron transport system of higher plant thylakoids implies a close coordination of the activities of PSI and PSII in linear electron flow (13,28). Although considerable efforts have been applied for the characterization of the detailed structure and functions of PSI and PSII, remarkably little attention has been given to the potential regulatory mechanisms needed to coordinate PSI and PSII activities. In this paper we examine the relationships between PSI and PSII photochemical activities in leaves using noninvasive spectroscopic techniques.Under conditions of increasing irradiance, the quantum efficiencies of both PSI and PSII decline. Oxidized P-7002 (p- 700+) is as good a quencher of excitation energy present in PSI as is reduced P-700 (P-700°) (25), but whereas quenching by P-7000 results in electron transport from PSI, quenching by P-700+ results only in thermal deactivation of the excitation energy. Consequently, the quantum efficiency of PSI is given by the degree of reduction of the P-700 pool (i.e. the amount of P-7000 relative to the total amount of P-700). Measurements of the redox state of P-700 in vivo have shown that the quantum efficiency of PSI is linearly related to the quantum efficiency for CO2 fixation when photorespiration is suppressed (28). With increasing irradiance the P-700 pool becomes progressively oxidized (15,16,28), and hence the quantum efficiency of PSI falls. The situation for PSII is complicated by the multiplicity of ways that PSII quantum efficiency can be modified (5, 16). The resolution of Chl fluorescence in vivo (which is largely from PSII) in terms of photochemical (qQ) and nonphotochemical quenching (qNp) has been described by Bradbury and Baker (3) and Deitz et al. (8). With increasing irradiance, qQ declines and qNP increases (8) but not in a way that can be simply related to the decline of 4PsHj (the quantum efficiency for electron transport by PSII) (29). Recently, Genty et al. ( 11) (Fv/Fm) (2,6,19).'The sequential arrangement of photosystems II and I in noncyclic electron transport (...

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Picosecond absorbance difference spectroscopy on the primary reactions and the antenna-excited states in Photosystem I particles

Cited by 135 publications

References 19 publications

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Changes in P-700 Oxidation during the Early Stages of the Induction of Photosynthesis

Determination of the primary charge separation rate in isolated photosystem II reaction centers with 500-fs time resolution

Relationship between the Quantum Efficiencies of Photosystems I and II in Pea Leaves

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