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1.
Characteristics of the Flash-induced 515 Nanometer Absorbance Change of Intact Isolated Chloroplasts
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In intact (type A) chloroplasts isolated from mesophyll protoplasts of maize (Zea mays L. convar. KSC 360) the flash-induced 515 nanometer absorbance change was much higher than in conventionally prepared (types B and C) chloroplasts. The 515 nanometer signal of type A chloroplasts exhibited a biphasic rise: the initial very fast rise (rise time «1 millisecond) was followed by a slow increase of absorbance (rise time 10 to 20 milliseconds). With decreasing degree of envelope retention the slow phase disappeared. Thus the biphasic rise of the flash-induced 515 nanometer absorbance change can be regarded as an attribute of intact chloroplasts. 相似文献
2.
Flash-induced primary charge separation, detected as electrochromic absorbance change, the operation of the cytochrome b/f complex and the redox state of the plastoquinone pool were measured in leaves, protoplasts and open-cell preparations of tobacco (Nicotiana tabacum L.), and in isolated intact chloroplasts of peas (Pisum sativum L.). Addition of 0.5–5 mM KCN to these samples resulted in a large increase in the slow electrochromic rise originating from the electrogenic activity of the cytochrome b/f complex. The enhancement was also demonstrated by monitoring the absorbance transients of cytochrome f and b
6 between 540 and 572 nm. In isolated, intact chloroplasts with an inhibited photosystem (PS) II, low concentrations of dithionite or ascorbate rendered turnover of only 60% of the PSI reaction centers, KCN being required to reactivate the remainder. Silent PSI reaction centers which could be reactivated by KCN were shown to occur in protoplasts both in the absence and presence of a PSII inhibitor. Contrasting spectroscopic data obtained for chloroplasts before and after isolation indicated the existence of a continuous supply of reducing equivalents from the cytosol.Our data indicate that: (i) A respiratory electron-transport pathway involving a cyanide-sensitive component is located in chloroplasts and competes with photosynthetic electron transport for reducing equivalents from the plastoquinone pool. This chlororespiratory pathway appears to be similar to that found in photosynthetic prokaryotes and green algae. (ii) There is an influx of reducing equivalents from the cytosol to the plastoquinone pool. These may be indicative of a complex respiratory control of photosynthetic electron transport in higher-plant cells.Abbreviations and symbols A515
flash-induced electrochromic absorbance change at 515 nm
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- PS
photosystem
- SHAM
salicylhydroxamic acid 相似文献
3.
Effect of dibromothymoquinone (DBMIB) on reduction rates of Photosystem I donors in intact chloroplasts 总被引:1,自引:0,他引:1
J Farineau H Bottin G Garab 《Biochemical and biophysical research communications》1984,120(3):721-725
Dual effect of dibromothymoquinone ( DBMIB ), inhibitor and reducing agent at the donor side of Photosystem I, was investigated in isolated intact chloroplasts by flash-induced absorbance changes at 820 and 515 nm. We show that in the absence of other electron donors, rereduction of P700+ by DBMIB proceeds at a very low rate (half-time of approximately 10 s) Dual effect of DBMIB explains that the initial rise of electrochromic absorbance change induced by repetitive flashes is usually not diminished while the slow rise is fully inhibited by this compound. 相似文献
4.
The flash-induced P515 absorbance change in intact chloroplasts consists of a fast and a slow phase. There is disagreement in the literature over the origin of the slow phase. Here we argue that the flash-induced slow phase in P515 absorbance change is composed of two different components. One component is most probably due to the electrogenic Q-cycle associated with the cytochrome b/f complex. The second component has decay kinetics that are much slower than the electrogenic reactions. We suggest that the second component is due to a non-electrogenic reaction.Abbreviations CCCP
carbonyl cyanide m-chlorophenylhydrazone
- DBMIB
2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone
- DCCD
dicyclohexylcarbodiimide
- DQH2
durohydroquinone
- MV
methylviologen
- P515
Absorbance change at 518 nm 相似文献
5.
Peters RL Bossen M van Kooten O Vredenberg WJ 《Journal of bioenergetics and biomembranes》1983,15(6):335-346
The P515 absorbance change upon single-turnover light flashes has been studied in intact leaves and isolated chloroplasts from spinach. A comparative study of the effects of preillumination on the kinetics of the P515 response and on the activity of the chloroplast ATPase has been made. The slow component (reaction 2) in the flash-induced P515 response normally present in dark-adapted chloroplasts is reduced or even absent under conditions in which the ATPase is activated by preillumination. This suppression of reaction 2 appeared to be temporary in leaves and chloroplasts; its duration in chloroplasts is shown to be dependent on the amount of ATP present. Tentoxin inhibits the preillumination-dependent suppression of reaction 2. 相似文献
6.
The retention of photosystems I and II and or RuDP carboxylase activity in chloroplasts isolated from the first leaves of Victory oat (Avena sativa L.) seedlings was followed as the chloroplasts senesced in darkness. Both photosystems (PS) I and II retained their full activity after 3 days at 1°C, while even after 7 days at 1°C around 80% of the activity was still present. After 3 days at 25°C, PS I lost only 20% and PS II 50% of the initial activity. Acid pH increased the rate of decay of both systems, PS II falling almost to zero after 3 days at pH 3.5 (at 25°C). The preparations were almost bacteria-free, and addition of antibiotics not only did not improve their stability, but accelerated the rates of loss of photosynthetic activity. This is held to indicate that the enzymes are undergoing some turnover even in isolated chloroplasts. If the leaves were allowed to senesce in the dark first and the chloroplasts then isolated, their photosynthetic activities had greatly decreased, showing that senescence is more rapid in situ than in isolation. Under these conditions PS I decayed more rapidly than PS II. Ribulosediphosphate carboxylase, as measured by CO2 fixation, declined more rapidly than the photosystems, though the addition of kinetin and indole-3-acetic acid somewhat decreased the rate of loss, at least for the first 24 h. When the intact (detached) leaves were held in the dark, the rate of oxygen evolution declined rapidly, but in monochromatic blue light (450 nm) at 25°C about 30% of the initial rate was retained after 72 h.Abbreviations BSA
bovine serum albumin, chl, chlorophyll
- DCPIP
dichlorophenol-indophenol
- EDTA
ethylenediaminetetraacetic acid
- IAA
indole-3-acetic acid
- PS
photosystem
- PVP
soluble polyvinylpyrrolidine
- RuDP
Ribulose-1,5-diphosphate
- TES
N-tris-(hydroxymethyl)-methyl-2-amino-ethane sulfonic acid 相似文献
7.
T. S. Desai 《Photosynthesis research》1990,25(1):17-24
The effect of ultraviolet light on thermoluminescence, oxygen evolution and the slow component of delayed light has been investigated in chloroplasts and Pothos leaves. All peaks including peak V (48°C) were inhibited by UV. However, the peak at 48°C which was induced by DCMU was enhanced following UV irradiation of chloroplasts at ambient temperature (23°C) whereas peak II (-12°C) and peak III (10°C) which were also induced by DCMU were inhibited. Chloroplasts treated with DCMU and dark incubated for several minutes at ambient temperature prior to recording of glow curves have also shown enhancement of peak at 48°C. A slow component of delayed light and photosystem II activity of chloroplasts were inhibited by UV whereas photosystem I activity was marginally affected. These results corroborate involvement of photosystem II in generating thermoluminescence and slow components of delayed light in photosynthetic materials.Abbreviations DCIP
Dichlorophenol Indophenol
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- DCQ
2,6 Dichloro-p-benzoquinone
- DLE
delayed light emission
- MOPS
Morpholino propane sulfonic acid
- PSI
Photosystem I
- PS II
Photosystem II
- TL
thermoluminescence 相似文献
8.
The flash-induced absorbance change measured at 518 nm (P515) in intact chloroplasts consists of at least 4 kinetically different components. Here the non-electrochromic component, either called phase d or reaction 3, is studied in some detail. The effect of DCMU, DQH2 and DBMIB on the amplitude of reaction 3 and the turnover of cytochrome f and P700 have been monitored, suggesting an involvement of photosystem 1 in the activation of the non-electrochromic absorbance change. This is confirmed by the parallel oscillation pattern found in P700 rereduction and the amplitude of reaction 3. 相似文献
9.
Effects of long-chained aliphatic amines on photosynthetic reactions in isolated spinach chloroplasts 总被引:1,自引:0,他引:1
The effect of six long-chained aliphatic amines on 14 CO2 -reduction, electron transport and the 515 nm absorbance change and shrinkage in isolated intact and broken chloroplasts from spinach ( Spinacia oleracea L. cv. Weibulls Medania) was investigated. Five of the six investigated amines affected photosynthesis in intact chloroplasts by inhibiting 14 CO2 -reduction. In broken chloroplasts the same amines uncoupled electron transport. When added to intact chloroplasts the five amines induced a light-dependent oxygen uptake leading to (he formation of hydrogen peroxide. The oxygen uptake was not due to the amines acting as Mehler reactants. The mode of action, different from that of simple aliphatic amines, was an effect on membrane integrity, first affecting the membrane potential. At higher amine concentrations a more general effect on the ion conditions in the thylakoids was evident. 相似文献
10.
The 515 nm absorbance change was studied in mesophyll and bundle sheath chloroplasts of maize, which contain different amounts of grana. The amplitude of the 515 nm signal (induced by 3 μs flashes repeated at 4 s intervals) has shown a correlation with the granum content of the samples. However, upon addition of N-methylphenazonium methosulphate the 515 nm signal became independent of the amount of grana: in agranal thylakoids a large pool of silent Photosystem I was activated and, as a result, the amplitude of the 515 nm signal of agranal chloroplasts increased to the level exhibited by granal chloroplasts.These data show that the 515 nm absorbance change is not limited to small closed vesicles like grana, but in the presence of suitable electron donors single lamellae of bundle sheath chloroplasts can also be active. 相似文献
11.
Robert L. A. Peters Olaf van Kooten Wim J. Vredenberg 《Journal of bioenergetics and biomembranes》1985,17(4):207-216
The effect of dicyclohexylcarbodiimide (DCCD) on the kinetics of the flashinduced P515 response and on the activity of the ATPase was investigated in isolated spinach chloroplasts. It was found that after the addition of 5×10–8 mol DCCD the rate of ATP hydrolysis induced by a period of 60 sec illumination was decreased to less than 5% of its original value. At this concentration, hardly any effect, if at all, could be detected on the kinetics of the flash-induced P515 response, neither in dark-adapted nor in light-activated chloroplasts. It was concluded that the presence of concentrations of DCCD, sufficiently high to affect the ATPase activity, does not affect the kinetics of the flash-induced P515 response. Since DCCD decreases the H+ permeability of the membrane-bound ATPase, it was concluded that this permeability coefficient for protons is not an important factor in the regulation of the flash-induced membrane potential and, therefore, does not affect the kinetics of the flash-induced P515 response. 相似文献
12.
The 515 nm absorbance change was studied in mesophyll and bundle sheath chloroplasts of maize, which contain different amounts of grana. The amplitude of the 515 nm signal (induced by 3 micro seconds flashes repeated at 4 s intervals) has shown a correlation with the granum content of the samples. However, upon addition of N-methylphenazonium methosulphate the 515 nm signal became independent of the amount of grana: in agranal thylakoids a large pool of silent Photosystem I was activated and, as a result, the amplitude of the 515 nm signal of agranal chloroplasts increased to the level exhibited by granal chloroplasts. These data show that the 515 nm absorbance change is not limited to small closed vesicles like grana, but in the presence of suitable electron donors single lamellae of bundle sheath chloroplasts can also be active. 相似文献
13.
Roles of the coupling factor in light-induced proton transportand 515-nm absorption change were investigated in chloroplastswashed with high concentrations of Tris salts (pH 7.2). Washingthe chloroplasts with Tris-HCl and Tris-HNO3 buffers diminishedboth the light-induced pH rise and absorbance change at 515-nm,while Tris-H2SO4 buffer was much less effective. Inhibited activitiescould be restored by replacement of the coupling factor afterextraction with EDTA. N,N'-dicyclohexylcarbodiimide also restoredboth activities. Effects of various anions on the proton pumpand 515-nm shift were also investigated. The order of effectivenesswas NO3>Cl>SO42. The role of thecoupling factor and its mode of action; the action mechanismsof Tris and anionsn energy transducing processes in chloroplasts,photophosphorylation, proton transport and absorbance changeat 515 nm, are discussed.
1Present address: Biology Department, College of Science andEngineering, Ryukyu University, Naha, Okinawa, Japan. (Received June 27, 1972; ) 相似文献
14.
Sharma S 《Journal of plant physiology》2007,164(10):1261-1267
This paper explores the effects of high light stress on Fe-deficient plants. Maize (Zea mays) plants were grown under conditions of Fe deficiency and complete nutrition. Attached, intact leaves of Fe-deficient and control plants were used for gas exchange experiments under suboptimal, optimal and photoinhibitory illumination. Isolated chloroplasts were used to study photosynthetic electron transport system, compromised by the induction of Fe deficiency. The reaction centers of PS II (measured as reduction of Q, the primary electron acceptor of P 680) and PS I (measured as oxidation of P 700) were estimated from the amplitude of light induced absorbance change at 320 and 700 nm, respectively. Plants were subjected to photoinhibitory treatment for different time periods and isolated chloroplasts from these plants were used for electron transport studies. Carbon dioxide fixation in control as well as in Fe-deficient plants decreased in response to high light intensities. Total chlorophyll, P 700 and Q content in Fe-deficient chloroplasts decreased, while Chl a/b ratio and Q/P 700 ratio increased. However, electron transport through PS II suffered more after photoinhibitory treatment as compared to electron transport through PS I or whole chain. Electron transfer through PS I+PS II, excluding the water oxidation complex showed a decrease in Fe-deficient plants. However, electron transport through this part of the chain did not suffer much as a result of photoinhibition, suggesting a defect in the oxidising side of PS II. 相似文献
15.
《BBA》1985,807(2):118-126
The influence of light quality and temperature on the distribution of the absorbed quanta between Photosystem I (PS I) and Photosystem II (PS II) in spinach leaves has been studied from the characteristics of chlorophyll fluorescence at 77 K. Leaves were preilluminated at different temperatures with either PS I light (to establish State 1) or with PS II light (to establish State 2), then cooled to 77 K and measured for fluorescence. In State 1, energy distribution appeared to be unaffected by temperature. A transition to State 2 resulted in an increase in PS I fluorescence and a decrease in the PS II fluorescence, indicating that a larger fraction of energy becomes redistributed to PS I. However, the extent of this redistribution varied: it was only small at 5°C to 20°C, but it largely increased at temperatures exceeding 20°C. This variation in the extent was related to a change in the mechanism of the state transition: at 15°C only the ‘initial’ distribution of energy was affected, while at 35°C an additional increase in the spill-over constant, kT (II → I), was included. It is assumed that under physiological conditions kT (II → I) is under the control of temperature rather than of light quality, whereby in leaves adapted to high physiological temperatures, the probability of energy spill-over from closed PS II centres to PS I is enhanced. In darkened leaves, the spill-over constant has been manipulated by preincubation at different temperatures. Then, the light-induced ‘energization’ of thylakoid membranes has been tested by measuring the light-induced electrochromic absorbance change at 515 nm (and light-induced light-scattering changes) in these leaves. The flash-induced 515 nm signal as well as the initial peak during a 1 s illumination were not affected by energy distribution. However, the amplitude of the pseudo-steady-state signal (as established during 1 s illumination) was considerably enhanced in leaves in which a larger fraction of the absorbed energy is distributed to PS I at the expense of PS II excitation. The results have been interpreted in such a way that an increase in energy spill-over from PS II to PS I favours a cyclic electron transport around PS I. It is discussed that changes in energy distribution (via spill-over) may serve to maintain a suitable balance between non-cyclic and cyclic electron transport in vivo. 相似文献
16.
Effects of high temperatures on the photosynthetic systems in spinach: Oxygen-evolving activities,fluorescence characteristics and the denaturation process 总被引:16,自引:0,他引:16
Yamane Yoshihiro Kashino Yasuhiro Koike Hiroyuki Satoh Kazuhiko 《Photosynthesis research》1998,57(1):51-59
Activities of oxygen evolution, fluorescence Fv (a variable part of chlorophyll fluorescence) values, and amounts of the 33 kDa protein remaining bound to the thylakoids in intact spinach chloroplasts were measured during and after high-temperature treatment. The following results were obtained. (1) Both the Fv value and the flash-induced oxygen evolution measured by an oxygen electrode were decreased at high temperatures, but they showed partial recovery when the samples were cooled down and incubated at 25°C for 5 min after high-temperature treatment. (2) Oxygen evolution was more sensitive to high temperatures than the Fv value, and the decrease in the Fv/Fm ratio at high temperatures rather corresponded to that in the oxygen evolution measured at 25°C after high-temperature treatment. (3) Photoinactivation of PS II was very rapid at high temperatures, and this seems to be a cause of the difference between the Fv values and the oxygen-evolving activities at high temperatures. (4) At around 40°C, the manganese-stabilizing 33 kDa protein of PS II was supposed to be released from the PS II core complexes during heat treatment and to rebind to the complexes when the samples were cooled down to 25°C. (5) At higher temperatures, the charge separation reaction of PS II was inactivated, and the PS II complexes became less fluorescent, which was recovered partially at 25°C. (6) Increases in the Fv value due to a large decrease in the electron flow from QA to QB became prominent after high-temperature treatment at around 50°C. This was the main cause of the discrepancy between the Fv values and the oxygen-evolving activities measured at 25°C. Relationship between the process of heat inactivation of PS II reaction center complexes and the fluorescence levels is discussed. 相似文献
17.
Jack Farineau 《Photosynthesis research》1993,36(1):25-34
Characteristics of thermoluminescence (TL) glow curves were studied in thylakoids (isolated from pea leaves) or in intact pea leaves after an exposure to very high light for 2 min in the TL device. The inhibition of photosynthesis was detected as decreases of oxygen evolution rates and/or of variable fluorescence.In thylakoids exposed to high light, then dark adapted for 5 min, a flash regime induced TL glow curves which can be interpreted as corresponding to special B bands since: 1) they can be fitted by a single B band (leaving a residual band at –5°C) with a lower activation energy and a shift of the peak maximum by –5 to –6°C and, 2) the pattern of oscillation of their amplitudes was normal with a period of 4 and maxima on flashes 2 and 6. During a 1 h dark adaptation, no recovery of PS II activity occurred but the shift of the peak maximum was decreased to –1 to –2°C, while the activation energy of B bands increased. It is supposed that centers which remained active after the photoinhibitory treatment were subjected to reversible and probably conformational changes.Conversely, in intact leaves exposed to high light and kept only some minutes in the dark, TL bands induced by a flash regime were composite and could be deconvoluted into a special B band peaking near 30°C and a complex band with maximum at 2–5°C. In the case of charging bands by one flash, this low temperature band was largely decreased in size after a 10 min dark adaptation period; parallely, an increase of the B band type component appeared. Whatever was the flash number, bands at 2–5°C were suppressed by a short far red illumination given during the dark adaptation period and only remained a main band a 20°C; therefore, the origin of the low temperature band was tentatively ascribed to recombinations in centers blocked in state S2QA
–QB
2–. In vivo, the recovery of a moderately reduced state in the PQ pool, after an illumination, would be slow and under the dependence of a poising mechanism, probably involving an electron transfer between cytosol and chloroplasts or the so-called chlororespiration process.Abbreviations Ea-
activation energy
- FR-
far-red
- MV-
methylviologen
- pBQ-
p-benzoquinone
- PQ-
plastoquinone
- PS II-
Photosystem II
- QA-
primary quinone electron acceptor of PS II
- QB-
secondary quinone electron acceptor of PS II
- TL-
thermoluminescence 相似文献
18.
Ellenson JL 《Plant physiology》1986,80(4):988-991
Studies of flash-induced delayed light emission profiles of dark-adapted intact plant tissues revealed a previously unreported component of plant luminescence. Only partially evident in intact chloroplasts and totally absent in broken chloroplasts, this peak may reflect the interaction of one or more light-activated enzyme systems with photosynthetic electron transport. 相似文献
19.
Formation of thermoluminescence signals is characteristics of energy- and charge storage in Photosystem II. In isolated D1/D2/cytochrome b-559 Photosystem II reaction centre preparation four thermoluminescence components were found. These appear at -180 (Z band), between -80 and -50 (Zv band), at -30 and at +35°C. The Z band arises from pigment molecules but not correlated with photosynthetic activity. The Zv and -30°C bands arise from the recombination of charge pairs stabilized in the Photosystem II reaction centre complex. The +35°C band probably corresponds to the artefact glow peak resulting from a pigment-protein-detergent interaction in subchloroplast preparations (Rózsa Zs, Droppa M and Horváth G (1989) Biochim Biophys Acta 973, 350–353).Abbreviations Chl
chlorophyll
- Cyt
cytochrome
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- D1
psbA gene product
- D2
psbD gene product
- P680
primary electron donor of PS II
- Pheo
pheophytin
- PS II
Photosystem II
- QA
primary quinone acceptor of PS II
- QB
secondary quinone acceptor of PS II
- RC
reaction centre of PS II
- TL
thermoluminescence 相似文献
20.
(1) The relationship between activation of the membrane-bound ATPase and the stimulation of dissipation of the flash-induced membrane potential by preillumination was studied in intact spinach leaves by measuring the ATPase activity of rapidly isolated chloroplasts and the decay of the flash-induced 515-nm absorbance change (ΔA515) in intact leaves. (2) The decay of ΔA515 was accelerated by preillumination. The ΔA515 decay in leaves treated with N,N′-dicyclohexylcarbodiimide (DCCD) became slower and was not accelerated by preillumination. However, treatment with DCCD did not lower the intensity of delayed fluorescence. (3) Membrane-bound ATPase of chloroplasts which were rapidly isolated from the preilluminated leaves (90 s preparation time) showed a higher activity (over 200 μmol Pi/mg chlorophyll per h in the case of 2-min preillumination) than that of chloroplasts isolated from dark-adapted leaves. (4) The acceleration of ΔA515 decay and the activation of ATPase showed similar dependences on illumination time in intact leaves. 3-(3′,4′-Dichlorophenyl)-1,1-dimethylurea, carbonyl cyanide p-chlorophenylhydrazone and DCCD inhibited the activation of ATPase and the acceleration of the ΔA515 decay by preillumination. (5) The ATPase activity of chloroplasts isolated from illuminated leaves showed a single exponential decay (‘dark inactivation in vitro’). The ATPase activity induced by illuminating the leaves became lower as the dark interval between illumination and the isolation of chloroplasts was increased (‘dark inactivation in vivo’). The time course of the decay of activity had a lag and showed a sigmoidal curve when plotted semilogarithmically. The decay had an apparent half-time of 25 min. (6) The recovery of the accelerated ΔA515 decay in preilluminated leaves to the original slow rate showed a sigmoidal decay similar to that of the activity of ATPase in intact leaves with a half-time of about 23 min in the dark. (7) It was concluded that the decay rate of ΔA515 reflected the chloroplast ATPase activity in intact leaves and that the ion conductance of thylakoid membrane was mainly determined by the H+ flux through the ATPase, the activity of which was increased after the formation of the high-energy state. 相似文献