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1.
Peter H. Homann 《Photosynthesis research》1988,15(3):205-220
Photosystem II membranes prepared from thylakoids of Phytolacca americana chloroplasts were depleted of their intrinsic 17 and 23 kDa polypeptides, and the effects of a reconstitution of these polypeptides on the Cl– requirements of O2 evolution activity were analyzed. It was found that the activating effectiveness of limiting amounts of added Cl– was increased several fold by an addition of the 23 kDa polypeptide. When it was supplemented by the 17 kDa species, only a small additional increase occurred, but Cl– retention in Cl– free media was enhanced greatly. Addition of the 17 kDa polypeptide alone was without effect because it is known that it cannot bind to its native site unless the 23 kDa polypeptide is in place.Optimal enhancements of the effectiveness of activating added Cl– were observed when the assays were done in the presence of the reconstituting polypeptides. When the reconstituting treatment with the polypeptides, and the assay of the Cl– relations, were separated, it was advantageous to have Cl– present in the reconstituting medium, and not to add Ca2+, another cofactor of photosynthetic water oxidation. Those requirements are attributed to the labilizing effects Cl– free conditions and divalent cations have on the association of especially the 23 kDa polypeptides with the water oxidizing complex, and to a possible aggregation of the membranes under the influence of Ca2+ which might have impeded proper polypeptide binding.Abbreviations Chl
Chlorophyll a+b
- Mes
4-morpholineethanesulfonic acid
- PSII
photosystem II
- SDS and LDS
sodium or lithium dodecylsulfate 相似文献
2.
Ruthenium red (RR) is known to be an inhibitor that binds to Ca2+ sites. It releases Ca2+ and Cl? together with the extrinsic polypeptide of 17 kDa associated with the oxygen evolving complex of photosystem II. In this work we used thermoluminescence to study S2/3QB? and S2QA? charge recombination. It is shown that RR produced a deeper inhibition of oxygen evolution compared with the effect of extrinsic polypeptide or Ca2+/Cl? depletion. Even though Mn is not released, the Mn cluster is disorganized by RR and the S1 → S2 transition is inhibited. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
3.
The precursor to the nuclear-coded 17 kDa early light-inducible protein (ELIP) of pea has been transported into isolated intact chloroplasts. The location of the mature protein in the thylakoid membranes was investigated after using cleavable crosslinkers such as DSP and SAND in conjunction with immuno-fractionation methods and by application of mild detergent fractionation. We show that ELIP is integrated into the membranes via the unstacked stroma thylakoids. After isolation of protein complexes by solubilization of membranes with Triton X-100 and sucrose density-gradient centrifugation the crosslinked ELIP comigrates with the PS II core complex. Using SAND we identified ELIP as a 41–51 kDa crosslinked product while with DSP four products of 80 kDa, 70 kDa, 50–42 kDa and 23–21 kDa were found. The immunoprecipitation data suggested that the D1-protein of the PS II complex is one of the ELIP partners in crosslinked products.Abbreviations chl
chlorophyll
- D1
herbicide-binding protein
- DSP
dithiobis-(succinimidylpropionate)
- ELIP
early light-inducible protein
- LHC I and LHC II
light-harvesting chlorophyll a/b complex associated with photosystem I or II
- PAGE
polyacrylamide gel electrophoresis
- poly(A)-rich RNA
polyadenyd mRNA
- PS I and PS II
photosystems I and II
- SAND
sulfosuccinimidyl 2-(m-azido-o-nitro-benzamido)-ethyl-1,3-dithiopropionate
- Triton X-100
octylphenoxypolyethoxyethanol 相似文献
4.
The oxygen evolving complex of photosystem II (PS II) contains three extrinsic polypeptides of approximate molecular weights 16, 23 and 33 kDa. These polypeptides are associated with the roles of Cl-, Ca2+ and Mn2+ in oxygen evolution. We have shown that selective removal of 16 and 23 kDa polypeptides from the above complex by NaCl washing of PS II enriched membrane fragments renders the PS II core complex more susceptible to the herbicide atrazine. On the other hand, when both native and depleted preparations were resupplied with exogenous Ca2+ and Cl-, we obtained a reduction of atrazine inhibition which was much stronger in the depleted preparations than in the native ones. It is concluded that removal of 16 and 23 kDa polypeptides in general, and disorganization of associated Ca2+ and Cl- in particular, enhances atrazine penetration to its sites of action in the vicinity of the PS II complex. The above could be interpreted if we assume a reduced plastoquinone affinity at the QB (secondary plastoquinone electron acceptor) pocket of D1 polypeptide following transmembranous modifications caused by the depletion of these polypeptides.Abbreviations CCCP
carbonylcyanide-m-chlorophenylhydrazone
- Chl
chlorophyll
- DCIP
2,6-dichlorophenolindophenol
- MES
2-(N-morpholino)ethanesulfonic acid
- PMSF
phenylmethylsul-phonyfluoride
- PS II
photosystem II
- PAGE
polyacrilamide gel electrophoresis 相似文献
5.
The linear, four-step oxidation of water to molecular oxygen by photosystem II requires cooperation between redox reactions driven by light and a set of redox reactions involving the S-states within the oxygen-evolving complex. The oxygenevolving complex is a highly ordered structure in which a number of polypeptides interact with one another to provide the appropriate environment for productive binding of cofactors such as manganese, chloride and calcium, as well as for productive electron transfer within the photoact. A number of recent advances in the knowledge of the polypeptide structure of photosystem II has revealed a correlation between primary photochemical events and a core complex of five hydrophobic polypeptides which provide binding sites for chlorophyll a, pheophytin a, the reaction center chlorophyll (P680), and its immediate donor, denoted Z. Although the core complex of photosystem II is photochemically active, it does not possess the capacity to evolve oxygen. A second set of polypeptides, which are water-soluble, have been discovered to be associated with photosystem II; these polypeptides are now proposed to be the structural elements of a special domain which promotes the activities of the loosely-bound cofactors (manganese, chloride, calcium) that participate in oxygen evolution activity. Two of these proteins (whose molecular weights are 23 and 17 kDa) can be released from photosystem II without concurrent loss of functional manganese; studies on these proteins and on the membranes from which they have been removed indicate that the 23 and 17 kDa species from part of the structure which promotes retention of chloride and calcium within the oxygen-evolving complex. A third water-soluble polypeptide of molecular weight 33 kDa is held to the photosystem II core complex by a series of forces which in some circumstances may include ligation to manganese. The 33 kDa protein has been studied in some detail and appears to promote the formation of the environment which is required for optimal participation by manganese in the oxygen evolving reaction. This minireview describes the polypeptides of photosystem II, places an emphasis on the current state of knowledge concerning these species, and discusses current areas of uncertainty concerning these important polypeptides.Abbreviations A 23187
ionophore that exchanges divalent cations with H+
- Chl
chlorophyll
- cyt
cytochrome
- DCPIP
dichlorophenolindophenol
- DPC
diphenylcarbazide
- EGTA
ethyleneglycoltetraacetic acid
- P680
the chlorophyll a reaction center of photosystem II
- pheo
pheophytin
- PQ
plastoquinone
- PS
photosystem
- QA and QB
primary and secondary plastoquinone electron acceptors of photosystem II
- Sn (n=0, 1, 2, 3, 4)
charge accumulating state of the oxygen evolving system
- Signals IIvf, IIf and IIs
epr-detectable free radicals associated with the oxidizing side of photosystem II
- Z
primary electron donor to the photosystem II reaction center
The survey of literature for this review ended in September, 1984. 相似文献
6.
Nikitishena OV Smolova TN Khatypov RA Shkuropatov AJ Klimov VV 《Biochemistry. Biokhimii?a》2002,67(3):364-371
A new pathway of photoinactivation of photosystem II (PS II) connected with irreversible photoaccumulation of reduced pheophytin (Ph) in isolated D1–D2–cytochrome b
559 complexes of reaction center (RC) of PS II was discovered. The inhibitory effects of white light illumination on photochemical activity of D1–D2–cytochrome b
559 complexes of RCs of photosystem II, isolated from pea chloroplasts, have been compared under anaerobic conditions in the absence and in the presence of sodium dithionite, electron transfer from which to the oxidized primary electron donor P680+ results in the photoaccumulation of anion-radical of the primary electron acceptor, PH. In both cases, prolonged illumination (1-5 min, 120 W/m2) led to a pronounced loss of the photochemical activity as it was monitored by measuring the amplitude of the reversible photoinduced absorbance changes at 682 nm related to the photoreduction of Ph. The extent of the photoinactivation depended on the illumination time and pH of the medium. At pH 8.0, the presence of dithionite during photoinactivation brought about a protective effect compared to that in a control sample. In contrast, lowering pH to 6.0 increased the sensitivity to photoinactivation in the dithionite containing samples. For 5 min irradiation, the photochemical activity in the absence and in the presence of dithionite decreased by 35 and 72%, respectively (this was accompanied by an irreversible bleaching of the pheophytin Qx absorption band at 542 nm). Degradation of the D1 and D2 proteins was not observed under these conditions. A subsequent addition of an electron acceptor, potassium ferricyanide, to the illuminated samples restored neither the amplitude of the signal at 682 nm nor absorption at 542 nm. It is suggested that at pH < 7.0 the photoaccumulated PH is irreversibly converted into a secondary, most probably protonated form, that does not lead to destruction of the RCs but prevents the photoformation of the primary radical pair [P680+PH]. A possible application of this effect to photoinactivation of PS II in vivo is discussed. 相似文献
7.
Structural roles of functional Ca2+ and Cl− ions in photosynthetic oxygen-evolving complexes (OEC) were studied using low- (640–350 cm−1) and mid- (1800–1200 cm−1) frequency S2/S1 Fourier transform infrared (FTIR) difference spectroscopy. Studies using highly active Photosystem (PS) II core particles from spinach enabled the detection of subtle spectral changes. Ca2+-depleted and Ca2+-reconstituted particles produced very similar mid- and low-frequency spectra. The mid-frequency spectrum was not affected by reconstitution with 44Ca isotope. In contrast, Sr2+-substituted particles showed unique spectral changes in the low-frequency Mn–O–Mn mode at 606 cm−1 as well as in the mid-frequency carboxylate stretching modes. The mid-frequency spectrum of Cl−-depleted OEC exhibited marked changes in the carboxylate stretching modes and the suppression of protein modes compared with that of Cl−-reconstituted OEC. However, Cl−-depletion did not exert significant effects on the low-frequency spectrum. 相似文献
8.
A comparative study of photosystem II complexes isolated from tobacco (Nicotiana tabacum L. cv. John William's Broadleaf) which contains normal stacked thylakoid membranes, and from two chlorophyll deficient tobacco mutants (Su/su and Su/su var. Aurea) which have low stacked grana or essentially unstacked thylakoids with occasional membrane doublings, has been carried out. The corresponding photosystem II complexes had an O2 evolving activity ranging from 290 (for the wild type) to 1100 mol O2 x mg chlorophyll-1 x h-1 (for the mutant Su/su var. Aurea). The reduced photosynthetic unit size was also obvious in the mangenese and cytochromeb559 content. The photosystem II complex from the wild type contained 4 Mn and 1 cytochromeb559 per 200 to 280 chlorophylls, while the corresponding value for the mutant Su/su var. Aurea was 4 Mn and 1 cytochromeb559 per 35 to 60 chlorophylls. We have also examined the polypeptide composition and show that the photosystem II complex from the wild type consisted of polypeptides of 48, 42, 33, 32, 30, 28, 23, 21, 18, 16 and 10 kDa, while the mutant complex mainly contained the polypeptides of 48, 42, 33, 32, 30, 28 and 10 kDa. In the mutant photosystem II complex the light-harvesting chlorophyll protein (peptide of 28 kDa) was reduced by a factor of 5 to 6 as compared to the wild type. With respect to the peptide composition and the photosynthetic unit size, the Triton-solubilized photosystem II complex from the mutant Su/su var. Aurea was very similar to O2 evolving photosystem II reaction center core complexes.Abbreviations PS
photosystem
- chl
chlorophyll
- LHCP
light-harvesting chlorophyll a/b protein complex 相似文献
9.
The reversible inhibition of Photosystem II by salicylaldoxime was studied in spinach D-10 particles by fluorescence, optical absorption, and electron spin resonance spectroscopy. In the presence of 15 mM salicylaldoxime, the initial fluorescence yield was raised to the level of the maximum fluorescence, indicating efficient charge recombination between reduced pheophytin (Ph) and P680+. In agreement with the rapid (ns) backreaction expected between Ph– and P680+, the optical absorption transient at 820 mm was not observed. When the particles were washed free of salicylaldoxime, the optical absorption transient resulting from the rereduction of P680+ was restored to the µs timescale. These results, along with the previously observed inhibition of electron transport reactions and diminution of the 515-nm absorption change in chloroplasts [Golbeck, J.H. (1980) Arch Biochem Biophys 202, 458–466], are consistent with a site of inhibition between Ph and QA in Photosystem II. ESR Signal IIf and Signal Its were abolished in the presence of 25 mM salicylaldoxime, but both signals could be recovered by washing the D-10 particles free of the inhibitor. The loss of Signal Ilf is most likely a consequence of the inhibition between Ph and QA; the rapid charge recombination between Ph– and P680+ would preclude electron transfer from an electron donor on the oxidizing side of Photosystem II. The loss of Signal Its may be due to a change in the environment of the donor complex such that the semiquinone radical giving rise to Signal Its interacts with a nearby reductant.Abbreviations D1
electron donor to P680+ in oxygen-inhibited chloroplasts
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- F0
prompt chlorophyll a fluorescence yield
- Fi
initial chlorophyll a fluorescence yield
- Fmax
maximum chlorophyll a fluorescence yield
- Fvar
variable chlorophyll a fluorescence yield
- FWHM
full width at half maximum
- Mes
2-(N-morpholino) ethanesulfonic acid
- P680
reaction center chlorophyll a of photosystem II
- Ph
pheophytin intermediate electron acceptor
- QA
primary quinone electron acceptor
- QB
secondary quinone electron acceptor
- Tris
tris(hydroxymethyl)aminomethane
- Z
electron donor to P680+ 相似文献
10.
Structural Effects of Cl and Other Anions on the Water Oxidizing Complex of Chloroplast Photosystem II
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Homann PH 《Plant physiology》1988,88(1):194-199
To further our understanding of the role of Cl− and certain other monovalent anions in the oxygen evolving photosystem II of chloroplasts, dissociating and stabilizing anion effects on the extrinsic 17 and 23 kilodalton polypeptides of the photosynthetic water oxidizing complex were investigated. It was found that (a) the dissociation of the two polypeptides in Cl− free media of pH ≈ 7 was enhanced by millimolar concentrations of the divalent anion SO42− and also by divalent cations like Mg2+ and Ca2+; (b) the dissociation was opposed by relatively low concentrations of monovalent anions with an order of effectiveness Cl− = Br− > NO3− > F− > ClO4−; (c) at molar concentrations, SO42− stabilized the binding of the 23 kilodalton polypeptide, while Cl− and Br− became dissociating agents, in agreement with studies by Blough and Sauer (1984 Biochim Biophys Acta 767: 377-381); (d) the binding of the polypeptides was strengthened at room temperature relative to 0°C, indicating an involvement of hydrophobic forces. It is suggested that a specific binding of Cl−, or certain substitutes, organizes the protein surfaces and/or the adjacent water layers in the water oxidizing complex in a way that not only stabilizes its assembly, but is essential for the catalytic mechanism as well. Binding of, or charge screening by, divalent ions interferes with this process. At high salt concentrations, all these effects are overridden by “lyotropic” actions of the solutes that affect the integrity of the water oxidizing protein complex by stabilizing or disrupting critical hydrophobic domains. 相似文献
11.
Treatment of Photosystem II particles from spinach chloroplasts with Triton X-100 with 2.6 M urea in the presence of 200 mM NaCl removed 3 polypeptides of 33 kDa, 24 kDa and 18 kDa, but left Mn bound to the particles. The (urea + NaCl)-treated particles could evolve oxygen in 200 mM, but not in 10 mM NaCl. Mn was gradually released with concomitant loss of oxygen-evolution activity in 10 mM NaCl but not in 200 mM Cl?. The NaCl-treated particles, which contained Mn and the 33-kDa polypeptide but not the 24-kDa and 18-kDa polypeptides, did not lose Mn or oxygen-evolution activity in 10 mM NaCl. These observations suggest that the 33-kDa polypeptide maintains the binding of Mn to the oxygen-evolution system and can be functionally replaced by 200 mM Cl?. 相似文献
12.
Exposure of Photosystem II (PS II) membrane particles from spinach to a temperature of 47 °C caused the rapid release of the 18 kDa protein in parallel to inactivation of oxygen evolution. Previously, it has been suggested that the first heat-jump response involves rapid Ca release from the Mn complex of O2-evolution, followed by the slower release of (2 + 2) MnII ions [Pospisil P et al. (2003) Biophys J 84: 1370–1386]. Here, the predicted biphasic MnII release to the bulk was verified by atomic absorption spectroscopy (AAS). Analysis of laser flash-induced delayed fluorescence transients suggests that the loss of the essential Ca ion from the Mn4Ca complex in the dark is due to the loss of the 18 kDa protein. The S2-state multiline EPR signal of the Mn complex was still generated in heat-treated PS II presumably lacking Ca, but retaining four Mn ions.Dedicated to Professor Norio Murata on the occasion of his retirement 相似文献
13.
A model for the mechanism of chloride activation of oxygen evolution in photosystem II 总被引:1,自引:0,他引:1
A hypothesis is proposed to explain the function of Cl- in activating the oxygenevolving complex (OEC) of photosystem II (PS II), based on the results of recent 35Cl-NMR studies. The putative mechanism involves Cl- binding to two types of sites. An intrinsic site is suggested to be composed of three histidyl residues (His 332 and His 337 from D1 and His 337 D2). It is proposed that Cl- binding to this site accelerates the abstraction of H+ from water by raising the pKa's of the histidine imidazole groups. Cl- binding also stimulates the transfer of H+ from this intrinsic site to a set of extrinsic sites on the 33 kD extrinsic polypeptide. The extrinsic Cl- binding sites are suggested to involve four protein domains that are linked together by salt-bridge contacts. Chloride and H+ donated from the intrinsic site attack these intramolecular salt-bridges in a defined sequence, thereby exposing previously inaccessible Cl- and H+ binding sites and stimulating the oxidation of water. This hypothesis also proposes a possible structure for the Mn active site within the D1/D2 complex. Specific amino-acid residues that are likely to participate as Mn lignads are identified on the lumenal portions of the D1 and D2 proteins that are different from those in the L and M subunits of photosynthetic bacteria; the choice of these residues is based on the metal coordination chemistry of these residues, their location within the polypeptide chain, the regularity of their spacing, and their conservation through evolution. The catalytic Mn-binding residues are suggested to be D-61, E-65, E-92, E-98, D-103; D-308, E-329, E-342 and E-333 in D1, and H-62, E-70, H-88, E-97, D-101; E-313, D-334, E-338 and E-345 in D2. Finally, this hypothesis identifies sites on both D2 and the 33 kD extrinsic polypeptide that might be involved in high- and low-affinity Ca2+ binding.To whom correspondence should be addressed 相似文献
14.
《BBA》1987,890(1):89-96
Electron donation to Photosystem II (PS II) by diphenylcarbazide (DPC) is interrupted by the presence of endogenous Mn in PS II particles. Removal of this Mn by Tris treatment greatly stimulates the electron transport with DPC as donor. Binding of low concentration of exogenous Mn(II) to Tris-treated PS II particles inhibits DPC photooxidation competitively with DPC. This phenomenon was used to locate a highly specific Mn(II) binding site on the oxidizing side of Photosystem II with dissociation constant about 0.15 μM. The binding of Mn(II) is electrostatic in nature. Its affinity depends not only on the ionic strength, but also on the anion species of the salt in the medium. The effectiveness in decreasing the affinity follows the order F− > SO2−4 > CH3COO− > CI− > Br− > NO3−. This observation is interpreted as follows: smaller ions, like F−, CH3COO−, and larger ions, like SO2−4, have inhibitory effects on Mn(II) binding, whereas ions with optimal size, like Cl−, Br− and NO3−, can stabilize the binding, resembling the anion requirement for reactivation of Cl−-depleted chloroplasts. We suggest that the binding site for Mn(II) we observed is the site for the endogenous Mn in the O2-evolving complex of PS II. This site remains after Tris treatment, which removes all the endogenous Mn as well as the three extrinsic proteins, indicating that it is on the intrinsic component(s) of PS II reaction centers. Furthermore, the Cl− requirement for O2 evolution may be attributed, at least partly to its stabilizing effect on Mn binding. 相似文献
15.
Edith L. Camm Beverley R. Green David R. Allred L. Andrew Staehelin 《Photosynthesis research》1987,13(1):69-80
Various washing procedures were tested on Triton-prepared PS II particles for their ability to remove the 33 kDa extrinsic polypeptide (33 kDa EP) associated with the water-splitting complex. Residual 33 kDa EP was evaluated by Coomassie blue staining of SDS gels of washed particles and by Western blotting with an antibody specific for the 33 kDa EP. A wash with 16 mM Tris buffer, pH 8.3, inhibited water-splitting activity but did not remove all the 33 kDa EP. Sequential washes with 30 mM octyl glucoside (pH 8.0 and 6.8), and a single wash with 0.8 M Tris were also ineffective in removing all the 33 kDa EP. Washing with 1 M CaCl2 was more effective in removing 33 kDa EP; while only a faint trace of protein was detectable by Coomassie-staining, immunoblotting revealed a considerable remainder. The treated particles retained some water-splitting activity. The two step procedure of Miyao and Murata (1984) involving 1 M NaCl and 2.3 M urea was most effective, removing all but a trace of antibody positive protein. Our finding suggests that (1) the degree of depletion of the 33 kDa EP cannot be judged on the basis of Coomassie stain alone, and (2) this extrinsic protein is very tightly associated with the membrane, perhaps via a hydrophilic portion of this otherwise hydrophilic protein. The results also suggest that the presence or absence of the 33 kDa protein per se is not the primary determinant of residual water splitting activity.Abbreviations Chl
chlorophyll
- DCPIP
dichlorophenolindophenol
- DPC
diphenolcarbazide
- DTT
dithiothreitol
- HEPES
N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid
- MES
2(N-morpholino)ethanesulfonic acid
- SDS
sodium dodecyl sulfate
- Tris
Tris(hydroxymethyl)aminomethane 相似文献
16.
Rapid and simple isolation of pure photosystem II core and reaction center particles from spinach 总被引:2,自引:2,他引:0
Peter J. van Leeuwen Maaike C. Nieveen Erik Jan van de Meent Jan P. Dekker Hans J. van Gorkom 《Photosynthesis research》1991,28(3):149-153
Pure and active oxygen-evolving PS II core particles containing 35 Chl per reaction center were isolated with 75% yield from spinach PS II membrane fragments by incubation with n-dodecyl--D-maltoside and a rapid one step anion-exchange separation. By Triton X-100 treatment on the column these particles could be converted with 55% yield to pure and active PS II reaction center particles, which contained 6 Chl per reaction center.Abbreviations Bis-Tris
bis[2-hydroxyethyl]imino-tris[hydroxymethyl]methane
- Chl
chlorophyll
- CP29
Chl a/b protein of 29 kDa
- Cyt b
559
cytochrome b
559
- DCBQ
2,5-dichloro-p-benzo-quinone
- LHC II
light-harvesting complex II, predominant Chl a/b protein
- MES
2-[N-Morpholino]ethanesulfonic acid
- Pheo
pheophytin
- PS H
photosystem II
- QA
bound plastoquinone, serving as the secondary electron acceptor in PS II (after Pheo)
- SDS
sodiumdodecylsulfate 相似文献
17.
Z. Krupa 《Photosynthesis research》1983,4(3):229-239
Thylakoid membranes obtained from bean chloroplasts treated with bean galactolipase or phospholipase A2 (from Crotalus terr. terr.) showed marked changes in their polypeptide patterns when separated on SDS-PAGE. The obtained results have been discussed with regard to the relationship between chloroplast lipids and polypeptides originating from chlorophyll-protein complexes of bean thylakoids. A coexistence between galactolipids and the peripheral antennae in PS I complex and LHCP3 as well as a conspicuous role of phospholipids in PSI and PSII centre chlorophyll-protein complexes has to be underlined.Abbreviations CP1
chlorophyll a-protein complex of PSI
- CPa
chlorophyll a-protein complex of PSII
- D10
digitonin subchloroplast particles enriched in PSII
- D144
digitonin subchloroplast particles enriched in PSI
- DCMU
3-(3,4-dichlorophenyl)-1,1-dimethylurea
- LHCP1–3
light harvesting chlorophyll a/b protein complexes
- PAGE
polyacrylamide gel electrophoresis
- PSI
photosystem I
- PSII
photosystem II
- SDS
sodium dodecyl sulphate
- TCA
trichloroacetic acid
- Tricine
N-Tris-(hydroxymethyl)-methylglycine
- Tris
Tris-(hydroxymethyl)-aminomethan 相似文献
18.
We investigated the activity of several anions at various sites on photosystem II, in particular those associated with the Cl- effect (anion binding-site I) and the HCO3
- effect (anion binding-site II). Chlorophyll a fluorescence changes were used to monitor partial photosystem II reactions either in the oxygen-evolving mechanism or involving endogenous quinone electron acceptors. We find that anions such as NO3
-, HCO3
-, HCO2
-, F-, NO2
-, and acetate can, depending on conditions, bind to either anion binding-site I, anion binding-site II, or both sites simultaneously. The anions N3
- and Au(CN)2
- are exceptions. In their presence, oxygen-consumption reactions are enhanced. The results demonstrate that an exclusive site or mode of action of an anion on photosystem II cannot be determined by measuring the Hill reaction alone. Anion interactions with photosystem II are shown to be very complex and, therefore, caution is advisable in interpreting related experiments. Carbonic anhydrase associated with photosystem II was also investigated as a possible target for some anion effects. In Cl--depleted thylakoids, NO3
-, stimulated both electron transport and carbonic anhydrase activity at low concentrations, while higher concentrations inhibited both. However, carbonic anhydrase was more sensitive to inhibition by NO3
- than was electron flow. Possible interpretations are discussed; the electron transport and carbonic anhydrase activity appear not to be functionally linked.Abbreviations ABSI
Anion binding-site(s) I associated with the oxygen-evolving mechanism
- ABSII
Anion binding-site(s) II, which controls quinone-related reactions on the electron-acceptor side of photosystem II
- OAc-
Acetate
- Chl
Chlorophyll
- DCMU
3—(3,4-dichlorophenyl)-1,1-dimethyl urea
- DCBQ
2,6-dichloro-p-benzoquinone
- DMBQ
2,5-dimethyl-p-benzoquinone
- Mes
2-[N-morpholino]ethanesulphonic acid
- Mops
3-[N-morpholino]propanesulphonic acid
- Tes
N-Tris[hydroxymethyl]methyl-2-aminoethanesulphonic acid
- Tricine
N-Tris[hydroxymethyl]methylglycine 相似文献
19.
Electron paramagnetic resonance (EPR) spectroscopy and O2 evolution assays were performed on photosystem II (PSII) membranes which had been treated with 1 M CaCl2 to release the 17, 23 and 33 kilodalton (kDa) extrinsic polypeptides. Manganese was not released from PSII membranes by this treatment as long as a high concentration of chloride was maintained. We have quantitated the EPR signals of the several electron donors and acceptors of PSII that are photooxidized or reduced in a single stable charge separation over the temperature range of 77 to 240 K. The behavior of the samples was qualitatively similar to that observed in samples depleted of only the 17 and 23 kDa polypeptides (de Paula et al. (1986) Biochemistry25, 6487–6494). In both cases, the S2 state multiline EPR signal was observed in high yield and its formation required bound Ca2+. The lineshape of the S2 state multiline EPR signal and the magnetic properties of the manganese site were virtually identical to those of untreated PSII membranes. These results suggest that the structure of the manganese site is unaffected by removal of the 33 kDa polypeptide. Nevertheless, in samples lacking the 33 kDa polypeptide a stable charge separation could only be produced in about one half of the reaction centers below 160 K, in contrast to the result obtained in untreated or 17 and 23 kDa polypeptide-depleted PSII membranes. This suggests that one function of the 33 kDa polypeptide is to stabilize conformations of PSII that are active in secondary electron transfer events.Abbreviations Chl-
chlorophyll
- DCBQ-
2,5-dichloro-p-benzoquinone
- DCMU-
(diuron) 3-(3,4-dichlorophenyl)-1,1-dimethylurea
- EGTA-
ethylene glycol bis-(-aminoethyl ether) N,N,N,N-tetraacetic acid
- EPR-
electron paramagnetic resonance
- HSB-
high salt buffer
- HSCaB-
high salt Ca2+ buffer
- kDa-
kilodalton
- MES-
2-(N-morpholino)ethanesulfonic acid
- P680-
primary electron donor in PSII
- PaGE-
polyacrylamide gel electrophoresis
- PSII-
Photosystem II
- QA-
primary quinone electron acceptor in PSII
- RB-
resuspension buffer
- TMPD-
N,N,N,N-tetramethyl-p- phenylenediamine
- Tris-
tris(hydroxymethyl)aminomethane
- TX100-
Triton X-100
- Z-
endogenous electron donor to P680+ 相似文献
20.
Christer Jansson Örjan Hansson Hans-Erik Åkerlund Lars-Erik Andreasson 《Biochemical and biophysical research communications》1984,124(1):269-276
EPR measurements on inside-out thylakoids revealed that salt-washing, known to inhibit oxygen evolution and release a 23 and a 16 kDa protein, induced a Signal IIf and decreased the EPR signal from state S2. Readdition of the released 23 kDa protein restored the oxygen evolution and decreased the Signal IIf, but did not relieve the decrease in the state S2 signal. It is suggested that salt-washing inhibits the electron transfer from the oxygen-evolving site to Z, the physiological donor to P680. In inhibited photosystem II units lacking Signal IIf, Z+ is rapidly reduced, possibly by a modified S-cycle unable to evolve oxygen. 相似文献