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1.
George M. Cheniae 《Photosynthesis research》1993,38(3):225-227
Twenty-five years of period-four O2-flash yield oscillation are celebrated with a personal recollection of the development of the Kok-Joliot model for photosynthetic oxygen evolution.Abbreviations PS II
Photosystem II
- RIAS
Research Institute for Advanced Studies 相似文献
2.
In oxygenic photosynthesis, a complete water oxidation cycle requires absorption of four photons by the chlorophylls of photosystem II (PSII). The photons can be provided successively by applying short flashes of light. Already in 1970, Kok and coworkers [Photochem Photobiol 11:457-475, 1970] developed a basic model to explain the flash-number dependence of O2 formation. The third flash applied to dark-adapted PSII induces the S3-->S4-->S0 transition, which is coupled to dioxygen formation at a protein-bound Mn4Ca complex. The sequence of events leading to dioxygen formation and the role of Kok's enigmatic S4-state are only incompletely understood. Recently we have shown by time-resolved X-ray spectroscopy that in the S3-->S0 transition an interesting intermediate is formed, prior to the onset of O-O bond formation [Haumann et al. Science 310:1019-1021, 2005]. The experimental results of the time-resolved X-ray experiments are discussed. The identity of the reaction intermediate is considered and the question is addressed how the novel intermediate is related to the S4-state proposed in 1970 by Bessel Kok. This leads us to an extension of the classical S-state cycle towards a basic model which describes sequence and interplay of electron and proton abstraction events at the donor side of PSII [Dau and Haumann, Science 312:1471-1472, 2006]. 相似文献
3.
Three extrinsic proteins (PsbO, PsbP and PsbQ), with apparent molecular weights of 33, 23 and 17 kDa, bind to the lumenal
side of Photosystem II (PS II) and stabilize the manganese, calcium and chloride cofactors of the oxygen evolving complex
(OEC). The effect of these proteins on the structure of the tetramanganese cluster, especially their possible involvement
in manganese ligation, is investigated in this study by measuring the reported histidine-manganese coupling [Tang et al. (1994)
Proc Natl Acad Sci USA 91: 704–708] of PS II membranes depleted of none, two or three of these proteins using ESEEM (electron
spin echo envelope modulation) spectroscopy. The results show that neither of the three proteins influence the histidine ligation
of manganese. From this, the conserved histidine of the 23 kDa protein can be ruled out as a manganese ligand. Whereas the
33 and 17 kDa proteins lack conserved histidines, the existence of a 33 kDa protein-derived carboxylate ligand has been posited;
our results show no evidence for a change of the manganese co-ordination upon removal of this protein. Studies of the pH-dependence
of the histidine–manganese coupling show that the histidine ligation is present in PS II centers showing the S2 multiline EPR signal in the pH-range 4.2–9.5.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
4.
A set of Mn K-edge XANES spectra due to the redox states S0–S3 of the OEC were determined by constructing a highly-sensitive X-ray detection system for use with physiologically native PS II membranes capable of cycling under a series of saturating laser-flashes. The spectra showed almost parallel upshifts with relatively high K-edge half-height energies given by 6550.9±0.2 eV, 6551.7±0.2 eV, 6552.5±0.2 eV and 6553.6±0.2 eV for the S0, S1, S2 and S3 states, respectively. The successive difference spectra between S0 and S1, S1 and S2, and S2 and S3 states were found to exhibit a similar peak around 6552–6553 eV, indicating that one Mn(III) ion or its direct ligand is univalently oxidized upon each individual S-state transition from S0 to S3. The present data, together with other observations of EPR and pre-edge XANES spectroscopy, suggest that the oxidation state of the Mn cluster undergoes a periodic change; S0: Mn(III,III,III,IV) S1: Mn(III,IV,III,IV) S2: Mn(III,IV,IV,IV) S3: Mn(IV,IV,IV,IV) or Mn(III,IV,IV,IV)·L+ with L being a direct ligand of a Mn(III) ion.Abbreviations Chl
chlorophyll
- D
tyrosine 160 on the D2 protein, an accessory electron donor in PS II
- D+
the oxidized form of D
- EDTA
ethylene-diaminetetraacetic acid
- EPR
electron paramagnetic resonance
- EXAFS
extended X-ray absorption fine structure
- HL
py-2,6-bis[bis(2-pyridylmethyl)aminomethyl]-4-methylphenol
- Mes
2-(N-morpholino)ethanesulfonic acid
- N4
py-tris(2-pyridylmethyl)amine
- OEC
oxygen evolving complex
- P680
primary electron donor of PS II
- PS II
Photosystem II
- Q400
a high spin Fe3+ of the iron-quinone acceptor complex in PS II
- SSD
solid state detector
- XAFS
X-ray absorption fine structure
- XANES
X-ray absorption near edge structure 相似文献
5.
Curtis W. Hoganson Demetrios F. Ghanotakis Gerald T. Babcock Charles F. Yocum 《Photosynthesis research》1989,22(3):285-293
Manganese in the oxygen-evolving complex is a physiological electron donor to Photosystem II. PS II depleted of manganese may oxidize exogenous reductants including benzidine and Mn2+. Using flash photolysis with electron spin resonance detection, we examined the room-temperature reaction kinetics of these reductants with Yz
+, the tyrosine radical formed in PS II membranes under illumination. Kinetics were measured with membranes that did or did not contain the 33 kDa extrinsic polypeptide of PS II, whose presence had no effect on the reaction kinetics with either reductant. The rate of Yz
+ reduction by benzidine was a linear function of benzidine concentration. The rate of Yz
+ reduction by Mn2+ at pH 6 increased linearly at low Mn2+ concentrations and reached a maximum at the Mn2+ concentrations equal to several times the reaction center concentration. The rate was inhibited by K+, Ca2+ and Mg2+. These data are described by a model in which negative charge on the membrane causes a local increase in the cation concentration. The rate of Yz
+ reduction at pH 7.5 was biphasic with a fast 400 s phase that suggests binding of Mn2+ near Yz
+ at a site that may be one of the native manganese binding sites.Abbreviations PS II
Photosystem II
- YD
tyrosine residue in Photosystem II that gives rise to the stable Signal II EPR spectrum
- Yz
tyrosine residue in Photosystem II that mediates electron transfer between the reaction center chlorophyll and the site of water oxidation
- ESR
electron spin resonance
- DPC
diphenylcarbazide
- DCIP
dichlorophenolindophenol 相似文献
6.
The influence of UV-B irradiation on photosynthetic oxygen evolution by isolated spinach thylakoids has been investigated using thermoluminescence measurements. The thermoluminescence bands arising from the S2QB
- (B band) and S2QA
– (Q band) charge recombination disappeared with increasing UV-B irradiation time. In contrast, the C band at 50°C, arising from the recombination of QA
- with an accessory donor of Photosystem II, was transiently enhanced by the UV-B irradiation. The efficiency of DCMU to block QA to QB electron transfer decreased after irradiation as detected by the incomplete suppression of the B band by DCMU. The flash-induced oscillatory pattern of the B band was modified in the UV-B irradiated samples, indicating a decrease in the number of centers with reduced QB. Based on the results of this study, UV-B irradiation is suggested to damage both the donor and acceptor sides of Photosystem II. The damage of the water-oxidizing complex does not affect a specific S-state transition. Instead, charge stabilization is enhanced on an accessory donor. The acceptor-side modifications decrease the affinity of DCMU binding. This effect is assumed to reflect a structural change in the QB/DCMU binding site. The preferential loss of dark stable QB
- may be related to the same structural change or could be caused by the specific destruction of reduced quinones by the UV-B light.Abbreviations Chl
chlorophyll
- DCMU
3-(3,4,-dichlorophenyl)-1,1-dimethylurea
- PS II
Photosystem II
- QA
first quinone electron acceptor of PS II
- QB
second quinone electron acceptor of PS II
- Tyr-D
accessory electron donor of PS II
- S0-S4
charge storage states of the water-oxidizing complex 相似文献
7.
An overview is presented of secondary electron transfer at the electron donor side of Photosystem II, at which ultimately two water molecules are oxidized to molecular oxygen, and the central role of manganese in catalyzing this process is discussed. A powerful technique for the analysis of manganese redox changes in the water-oxidizing mechanism is the measurement of ultraviolet absorbance changes, induced by single-turnover light flashes on dark-adapted PS II preparations. Various interpretations of these ultraviolet absorbance changes have been proposed. Here it is shown that these changes are due to a single spectral component, which presumably is caused by the oxidation of Mn(III) to Mn(IV), and which oscillates with a sequence +1, +1, +1, –3 during the so-called S0 S1 S2 S3 S0 redox transitions of the oxygen-evolving complex. This interpretation seems to be consistent with the results obtained with other techniques, such as those on the multiline EPR signal, the intervalence Mn(III)-Mn(IV) transition in the infrared, and EXAFS studies. The dark distribution of the S states and its modification by high pH and by the addition of low concentrations of certain water analogues are discussed. Finally, the patterns of proton release and of electrochromic absorbance changes, possibly reflecting the change of charge in the oxygen-evolving system, are discussed. It is concluded that nonstoichiometric patterns must be considered, and that the net electrical charge of the system probably is the highest in state S2 and the lowest in state S1. 相似文献
8.
9.
In Photosystem II (PS II), water is oxidized to molecular oxygen and plastoquinone is reduced to plastoquinol. The oxidation of water requires the accumulation of four oxidizing equivalents, through the so-called S-states of the oxygen evolving complex; the production of plastoquinol requires the accumulation of two reducing equivalents on a bound plastoquinone, QB. It has been generally believed that during the flash-induced transition of each of the S-states (Sn Sn+1, where n=0, 1, 2 and 3), a certain small but equal fraction of the PS II reaction centers are unable to function and, thus, miss being turned over. We used thoroughly dark-adapted thylakoids from peas (Pisum sativum) and Chenopodium album (susceptible and resistant to atrazine) starting with 100% of the oxygen evolving complex in the S1 state. Thylakoids were illuminated with saturating flashes, providing a double hit parameter of about 0.07. Our experimental data on flashnumber dependent oscillations in the amount of oxygen per flash fit very well with a binary pattern of misses: 0, 0.2, 0, 0.4 during S0 S1, S1 S2, S2 S3 and S3 S0 transitions. Addition of 2 mM ferricyanide appears to shift this pattern by one flash. These results are consistent with the bicycle model recently proposed by V. P. Shinkarev and C. A. Wraight (Oxygen evolution in photosynthesis: From unicycle to bicycle, 1993, Proc Natl Acad Sci USA 90: 1834–1838), where misses are due to the presence of P+ or QA
- among the various equilibrium states of PS II centers.Abbreviations
miss parameter
-
double hit parameter
- PS II
Photosystem II
- QA
primary one-electron acceptor of PS II, a plastoquinone molecule
- QB
secondary plastoquinone two-electron acceptor of PS II
- S-states (Sn, where n=0, 1, 2, 3 or 4)
redox states of the oxygen evolving complex 相似文献
10.
Vitaly D. Samuilov Gernot Renger Vladimir Z. Paschenko Alexander V. Oleskin Michail V. Gusev Olga N. Gubanova Sergei S. Vasil'ev Eugene L. Barsky 《Photosynthesis research》1995,46(3):455-465
The protonophoric uncouplers carbonyl cyanide m-chlorophenylhydrazone (CCCP), 2,3,4,5,6-pentachlorophenol (PCP) and 4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazole (TTFB) inhibited the Hill reaction with K3[Fe(CN)6] (but not with SiMo) in chloroplast and cyanobacterial membranes (the I50 values were approx. 1–2, 4–6 and 0.04–0.10 M, respectively). The inhibition is due to oxidation of the uncouplers on the Photosystem II donor side (ADRY effect) and their subsequent reduction on the acceptor side, ie. to the formation of a cyclic electron transfer chain around Photosystem II involving the uncouplers as redox carriers. The relative amplitude of nanosecond chlorophyll fluorescence in chloroplasts was increased by DCMU or HQNO and did not change upon addition of uncouplers, DBMIB or DNP-INT; the HQNO effect was not removed by the uncouplers. The uncouplers did not inhibit the electron transfer from reduced TMPD or duroquinol to methylviologen which is driven by Photosystem I. These data show that CCCP, PCP and TTFB oxidized on the Photosystem II donor side are reduced by the membrane pool of plastoquinone (Qp) which is also the electron donor for K3 [Fe(CN)6] in the Hill reaction as deduced from the data obtained in the presence of inhibitors. Inhibition of the Hill reaction by the uncouplers was maximum at the pH values corresponding to the pK of these compounds. It is suggested that the tested uncouplers serve as proton donors, and not merely as electron donors on the oxidizing side of Photosystem II.Abbreviations ADRY-
acceleration of the deactivation reactions of the water-splitting enzyme system Y
- ANT2p-
2-(3-chloro-4-trifluoromethyl) anilino-3,5-dinitrothiophene
- CCCP-
carbonyl cyanide m-chlorophenylhydrazone
- DBMIB-
2,5-dibromo-3-methyl 6-isopropyl-p-benzoquinone
- DCMU-
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- DNP-INT-
2-iodo-6-isopropyl-3-methyl 2,4,4-trinitrodiphenyl ether
- DPC-
1,5-diphenylcarbazide
- DPIP-
2,6-dichlorophenolindophenol
- FCCP-
carbonyl cyanide p-trifuoromethoxyphenylhydrazone
- FeCy-
potassium ferricyanide
- HQNO-
2-n-heptyl-4-hydroxyquinoline N-oxide
- (MN)4-
the tetranuclear Mn cluster of water oxidizing complex
- P680-
photoactive Chl of the reaction center of Photosystem II
- PCP-
2,3,4,5,6-pentachlorophenol
- PS-
photosystem
- QA and QB-
primary and secondary plastoquinones of PS II
- QC and QZ-
plastoquinone binding sites in the cytochrome blf complex
- Qp-
membrane pool of plastoquinone
- SiMo-
sodium silicomolybdate
- TMPD-
N,N,N-tetramethyl-p-phenylenediamine
- TTFB-
4,5,6,7-tetrachloro-2-trifluoromethylbenzimidazole
- WOC-
water oxidixing complex
- YZ-
tyrosine-161 of the Photosystem II D1 polypeptide 相似文献
11.
12.
Haddy A 《Photosynthesis research》2007,92(3):357-368
Electron paramagnetic resonance (EPR) spectroscopy is a valuable tool for understanding the oxidation state and chemical environment
of the Mn4Ca cluster of photosystem II. Since the discovery of the multiline signal from the S2 state, EPR spectroscopy has continued to reveal details about the catalytic center of oxygen evolution. At present EPR signals
from nearly all of the S-states of the Mn4Ca cluster, as well as from modified and intermediate states, have been observed. This review article describes the various
EPR signals obtained from the Mn4Ca cluster, including the metalloradical signals due to interaction of the cluster with a nearby organic radical. 相似文献
13.
Photosystem II particles were prepared from spinach chloroplasts with Triton X-100, and treated with 1.0 M NaCl to remove polypeptides of 24 kDa and 18 kDa and to reduce the photosynthetic oxygen-evolution activity by about half. Oxygen-evolution activity was restored almost to the original level with 10 mM Ca2+, in a similar manner to the rebinding of 24-kDa polypeptide. Other cations such as magnesium, sodium and manganese ions could not restore any oxygen-evolution activity. These observations, together with a kinetic analysis, suggest that Ca2+ can be substituted for the 24-kDa polypeptide in photosynthetic oxygen evolution in Photosystem II particles. 相似文献
14.
Mayer JM Rhile IJ Larsen FB Mader EA Markle TF DiPasquale AG 《Photosynthesis research》2006,87(1):21-24
The coupling of proton and electron transfers is a key part of the chemistry of photosynthesis. The oxidative side of photosystem
II (PS II) in particular seems to involve a number of proton-coupled electron transfer (PCET) steps in the S-state transitions.
This mini-review presents an overview of recent studies of PCET model systems in the authors’ laboratory. PCET is defined
as a chemical reaction involving concerted transfer of one electron and one proton. These are thus distinguished from stepwise
pathways involving initial electron transfer (ET) or initial proton transfer (PT). Hydrogen atom transfer (HAT) reactions
are one class of PCET, in which H+ and e
− are transferred from one reagent to another: AH+B→A+BH, roughly along the same path. Rate constants for many HAT reactions
are found to be well predicted by the thermochemistry of hydrogen transfer and by Marcus Theory. This includes organic HAT
reactions and reactions of iron-tris(α-diimine) and manganese-(μ-oxo) complexes. In PS II, HAT has been proposed as the mechanism
by which the tyrosine Z radical (YZ) oxidizes the manganese cluster (the oxygen evolving complex, OEC). Another class of PCET reactions involves transfer of
H+ and e
− in different directions, for instance when the proton and electron acceptors are different reagents, as in AH–B+C+→A–HB++C. The oxidation of YZ by the chlorophyll P680 + has been suggested to occur by this mechanism. Models for this process – the oxidation of phenols
with a pendent base – are described. The oxidation of the OEC by YZ could also occur by this second class of PCET reactions, involving an Mn–O–H fragment of the OEC. Initial attempts to model
such a process using ruthenium-aquo complexes are described.
An erratum to this article can be found at 相似文献
15.
Alan Stemler 《BBA》1980,593(1):103-112
In broken chloroplasts the presence of 100 mM sodium formate at pH 8.2 will specifically lengthen the Photosystem II relaxation times of the reactions S′2 → S3 and S′3 → S0. Rates of reactions S′0 → S1 and S′1 → S2 remain unaffected. Evidence is presented which indicates the discrimination among S-states by formate cannot be attributed to a block imposed on the reducing side of Photosystem II. The results are interpreted in context of the known interaction of formate and CO2 which is bound to the Photosystem II reaction center complex. It is proposed that those S-state transitions which show extended relaxation times in the presence of formate must result in the momentary release and rebinding of CO2. Furthermore since formate is acting on the oxygen-evolving side of Photosystem II, it would seem that CO2 is released in reactions that occur there. A chemical model of oxygen evolution is presented. It is based on the hypothesis that hydrated CO2 is the immediate source of photosynthetically evolved oxygen and explains why, under certain conditions formate slows only the S-state transitions S′2 → S3 and S′3 → S0. 相似文献
16.
We present here an improvement to the analysis of oxygen evolution with four sigma coefficients (4-S) by computing z, the sum of the S-state probabilities, which was introduced earlier (Delrieu and Rosengard 1987, Biochim Biophys Acta 892: 163–171). We demonstrate that z is equal to the ratio of two consecutive Mean Y (the estimation of the steady state oxygen production based on local properties) found by three sigma analysis. The quantity z is useful for computing double-hits, and for showing the inactivation/activation processes of PS II complexes. Three sigma analysis assumes z=1 exactly; since this is not verified, it is argued that four sigma analysis is closer to the real workings of the water oxidizing complex. Oxygen evolution can then be interpreted in the frame of a modified Kok's model where the sum of the probabilities equals z. We therefore suggest that the closer fitting of four sigma analysis to oxygen production data is not simply due to an extra, unnecessary variable, but to the fact that PS II complexes can be inactivated and reactivated under flashing light. Finally, in order to facilitate the use of four sigma analysis, a computer program is made available upon request. 相似文献
17.
18.
In vivo effect of abscisic acid (ABA) on photosynthetic oxygen evolution was investigated in barley chloroplasts. The most important kinetic parameters of O2-producing reactions were changed. The results show inhibition of the O2-flash yields at ABA concentrations of 10 mol/l and 100 mol/l and an increase in the degree of damping of the oscillations. ABA has a marked effect on the distribution of the oxygenevolving centers in S0 and S1 states and on sum of the centers (S0+S1) estimated according to the Kok model. In addition, the amplitude and the shape of the initial oxygen burst under continuous illumination are also significantly altered. At a concentration of 100 mol/l, ABA strongly inhibits Hill reaction activity measured by DCPIP reduction. The results cannot be explained by the hypothesis of socalled stomata effect. On the other hand, no effects were observed on the investigated parameters in experiments involving ABA applied in vitro to isolated chloroplasts. It is hypothesized that ABA disrupts the granal chloroplasts structure and raises the degree of participation of the cooperative mechanism of O2-evolution connected with the functioning of PS II centers in the stroma situated thylakoids.Abbreviations DCPIP
2,6-Dichlorophenolindophenol
- DCMU
3-(3,4-dichlorophenil)-1,1-dimethylurea
- HEPES
N-2-Hydroxyethylpiperazine-N-2-ethane sulfonic acid
- PSII
photosystem II
- RubisCO
Ribulose-1,5-bis-phosphate carboxylase-oxygenase 相似文献
19.
Noguchi T 《Photosynthesis research》2007,91(1):59-69
The molecular mechanism of photosynthetic oxygen evolution remains a mystery in photosynthesis research. Although recent X-ray crystallographic studies of the photosystem II core complex at 3.0-3.5 A resolutions have revealed the structure of the oxygen-evolving center (OEC), with approximate positions of the Mn and Ca ions and the amino acid ligands, elucidation of its detailed structure and the reactions during the S-state cycle awaits further spectroscopic investigations. Light-induced Fourier transform infrared (FTIR) difference spectroscopy was first applied to the OEC in 1992 as detection of its structural changes upon the S(1)-->S(2) transition, and spectra during the S-state cycle induced by consecutive flashes were reported in 2001. These FTIR spectra provide extensive structural information on the amino acid side groups, polypeptide chains, metal core, and water molecules, which constitute the OEC and are involved in its reaction. FTIR spectroscopy is thus becoming a powerful tool in investigating the reaction mechanism of photosynthetic oxygen evolution. In this mini-review, the measurement method of light-induced FTIR spectra of OEC is introduced and the results obtained thus far using this technique are summarized. 相似文献
20.
Suleyman I. Allakhverdiev Hidenori Hayashi Yoko Fujimura Vyacheslav V. Klimov Norio Murata 《Photosynthesis research》1993,35(3):345-349
We examined the effects of o-phenanthroline and LiClO4 on oxygen evolution and electron transport in the Photosystem 2 complex of the pea. Treatment of Photosystem 2 particles with a combination of 3.0 mM o-phenanthroline and 1.0 M LiClO4 for 30–40 min at 0°C decreased the oxygen-evolving activity with the electron acceptor (either phenyl-p-benzoquinone or 2,6-dichlorophenol indophenol) to less than 5% of the original level. However with the same treatment, the electron-transport activity from an artificial electron donor, 1,5-diphenylcarbohydrazide, to 2,6-dichlorophenol indophenol remained at 60% of the original activity. The amount of manganese in the Photosystem 2 complex decreased in parallel with the loss of oxygen evolution following treatment. These observations suggest that the treatment of the Photosystem 2 complex with o-phenanthroline and LiClO4 inhibits electron transport on the oxygen-evolving side much more significantly than on the electron-acceptor side.Abbreviations Chl
chlorophyll
- DCPIP
2,6-dichlorophenol indophenol
- DPC
1,5-diphenylcarbo hydrazide
- EDTA
ethylenediaminetetraacetic acid
- Hepes
4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid
- Mes
4-morpholineethanesulfonic acid
- PBQ
phenyl-p-benzoquinone
- PS 2
Photosystem 2 相似文献