Information on EC 1.10.9.1 - plastoquinol-plastocyanin reductase

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The expected taxonomic range for this enzyme is: Eukaryota, Bacteria

EC NUMBER
COMMENTARY hide
1.10.9.1
-
RECOMMENDED NAME
GeneOntology No.
plastoquinol-plastocyanin reductase
REACTION
REACTION DIAGRAM
COMMENTARY hide
ORGANISM
UNIPROT
LITERATURE
plastoquinol + 2 oxidized plastocyanin + 2 H+[side 1] = plastoquinone + 2 reduced plastocyanin + 4 H+[side 2]
show the reaction diagram
REACTION TYPE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
oxidation
-
-
-
-
redox reaction
-
-
-
-
reduction
-
-
-
-
PATHWAY
BRENDA Link
KEGG Link
MetaCyc Link
photosynthesis light reactions
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-
Photosynthesis
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-
SYSTEMATIC NAME
IUBMB Comments
plastoquinol:oxidized-plastocyanin oxidoreductase
Contains two b-type cytochromes, two c-type cytochromes (cn and f), and a [2Fe-2S] Rieske cluster. The enzyme plays a key role in photosynthesis, transferring electrons from photosystem II (EC 1.10.3.9) to photosystem I (EC 1.97.1.12). Cytochrome c-552 can act as acceptor instead of plastocyanin, but more slowly. In chloroplasts, protons are translocated through the thylakoid membrane from the stroma to the lumen. The mechanism occurs through the Q cycle as in EC 1.10.2.2, quinol---cytochrome-c reductase (complex III) and involves electron bifurcation.
CAS REGISTRY NUMBER
COMMENTARY hide
79079-13-3
-
ORGANISM
COMMENTARY hide
LITERATURE
UNIPROT
SEQUENCE DB
SOURCE
Acutodesmus obliquus
-
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
strain SAG 7.73
-
-
Manually annotated by BRENDA team
strain SAG 7.73
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
Cyanobacterium sp.
-
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
L. var. Steffi
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-
Manually annotated by BRENDA team
plastid cytochrome b6f-complex iron-sulfur subunit protein
TrEMBL
Manually annotated by BRENDA team
Lactuca sp.
lettuce
-
-
Manually annotated by BRENDA team
pea
-
-
Manually annotated by BRENDA team
-
-
-
Manually annotated by BRENDA team
cyanobacterium, PCC 7002, wild type and mutants
-
-
Manually annotated by BRENDA team
GENERAL INFORMATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
evolution
-
cytochrome bc1-complexes of animals and bacteria, as well as related cytochrome b6 f complexes of plants and cyanobacteria are dimeric quinol:cytochrome c/plastocyanin oxidoreductases capable of translocating protons across energy-converting membranes. These enzymes oxidize two quinolmolecules in their catalytic centers P to yield one quinol molecule in another catalytic center N. The simplest cytochrome bc1-complexes of Rhodobacter capsulatus, which contains only 3 subunits, matches the structure of the three catalytic subunits of mitochondrial bc1
physiological function
additional information
SUBSTRATE
PRODUCT                       
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
Reversibility
r=reversible
ir=irreversible
?=not specified
duroquinol + plastocyanin
duroquinone + reduced plastocyanin
show the reaction diagram
plastoquinol + 2 oxidized plastocyanin
plastoquinone + 2 reduced plastocyanin
show the reaction diagram
-
-
-
-
?
plastoquinol + 2 oxidized plastocyanin + 2 H+[side 1]
plastoquinone + 2 reduced plastocyanin + 2 H+[side 2]
show the reaction diagram
-
-
-
-
?
plastoquinol + ?
plastoquinone + ?
show the reaction diagram
-
-
-
-
?
plastoquinol + cytochrome c6
plastoquinone + reduced cytochrome c6
show the reaction diagram
-
-
-
-
?
plastoquinol + plastocyanin
plastoquinone + reduced plastocyanin
show the reaction diagram
additional information
?
-
NATURAL SUBSTRATES
NATURAL PRODUCTS
REACTION DIAGRAM
ORGANISM
UNIPROT
COMMENTARY
(Substrate) hide
LITERATURE
(Substrate)
COMMENTARY
(Product) hide
LITERATURE
(Product)
REVERSIBILITY
r=reversible
ir=irreversible
?=not specified
plastoquinol + 2 oxidized plastocyanin + 2 H+[side 1]
plastoquinone + 2 reduced plastocyanin + 2 H+[side 2]
show the reaction diagram
-
-
-
-
?
plastoquinol + cytochrome c6
plastoquinone + reduced cytochrome c6
show the reaction diagram
-
-
-
-
?
plastoquinol + plastocyanin
plastoquinone + reduced plastocyanin
show the reaction diagram
additional information
?
-
COFACTOR
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
METALS and IONS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
2Fe-2S
Fe2+
-
Rieske iron-sulfur protein, ISP, containing a [2Fe-2S] cluster, conformational flexibility of the cyt b6 f ISP subunit
Iron
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PetC1 is the major Rieske iron-sulfur protein in the cytochrome b6f complex. PetC2 can partly replace the dominating Rieske isoform PetC1, PetC3 is unable to functionally replace either PetC1 or PetC2 and may have a special function involving a special donor with a lower redox potential than plastoquinone
Zn2+
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concurrent action of Zn2+ ions on the re-reduction of cytochrome c1 by the Rieske protein, voltage generation, and proton release from the bc1
INHIBITORS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
(E)-beta-methoxyacrylate stilbene
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weak inhibition, retards concurrently the flashinduced re-reduction of cytochrome f, the oxidation of cytochrome b6 and the onset of voltage generation, thereby hardly affecting the rate of the flash-induced cytochrome b6 reduction and the steady turnover of the bf
2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone
2,5-dibromo-3-methyl-6-isopropylbenzoquinone
2,5-dibromo-6-methyl-3-isopropyl-1,4-benzochinon
2-azido-2',2,4'-trinitro-6-sec-butyl-diphenyl ether
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DNP-ANT, 50% inhibition at 0.00015 mM
2-heptyl-4-hydroxyquinoline N-oxide
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inhibition at low concentrations, 0.001-0.002 mM
2-Iodo-6-isopropyl-3-methyl-2',2,4'-trinitrodiphenyl ether
2-n-Nonyl-4-hydroxyquinoline N-oxide
2-nonyl-4-hydroxyquinoline N-oxide
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3-(3',4'-dichlorophenyl)-1,1-dimethylurea
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3-Azido-2-methyl-5-methoxy-6-(3,7-dimethyloctyl)-1,4-benzoquinone
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azido-Q, 45% inhibition at 30 mol inhibitor per 1 mol cytochrome f
4-nitroquinoline-N-oxide
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NQNO
5-(n-undecyl)-6-hydroxy-4,7-dioxobenzothiazole
8-hydroxy-5,7-dimethoxy-3-methyl-2-tridecyl-4H-chromen-4-one
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aurachin A
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weak inhibitor
aurachin B
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weak inhibitor
aurachin C
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-
aurachin D
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bathopheneanthroline
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carbonyl cyanide p-trifluoro-methoxy-phenylhydrazone
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slight inhibition
Cu2+
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competitive with plastoquinol
Stigmatellin
tridecyl-stigmatellin
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-
Triton X-100
Zn2+
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competitive with plastoquinol, non-competitive with cytochrome c
additional information
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ACTIVATING COMPOUND
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
3-chloro-5-hydroxy-2-methyl-6-decyl-1,4-benzoquinone
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activation with substrate 2,3-dimethyl-6-geranyl-1,4-benzoquinone
nigericin
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0.0005 mg/ml
valinomycin
additional information
-
the bf complex, however, can be dark-activated via reduction of heme cn by ferredoxin
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KM VALUE [mM]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.0032 - 0.0039
2,3-dimethyl-6-geranyl-1,4-benzoquinol
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depending on presence of activator
0.009
plastoquinol
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0.02
plastoquinol-1
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0.04
plastoquinol-9
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TURNOVER NUMBER [1/s]
SUBSTRATE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
IMAGE
0.333
cytochrome c1
Anabaena variabilis
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4.17 - 34
cytochrome f
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additional information
additional information
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SPECIFIC ACTIVITY [µmol/min/mg]
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
additional information
pH OPTIMUM
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pH RANGE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
pI VALUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
6.7
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cytochrome f
6.8
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Rieske iron-sulfur protein
8.1
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subunit VI
9
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cytochrome b6
SOURCE TISSUE
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
SOURCE
LOCALIZATION
ORGANISM
UNIPROT
COMMENTARY hide
GeneOntology No.
LITERATURE
SOURCE
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cytochrome b6f is a dimeric protochlorophyll a binding complex in etioplasts
Manually annotated by BRENDA team
MOLECULAR WEIGHT
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
20000
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Rieske FeS-Protein, SDS-PAGE
95000
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calculation from subunit size assuming stoichiometry of 1:1:1:1
128000
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molecular mass added up after SDS-PAGE of subunits
142000
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calculation from cytochrome f content
160000
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calculation from ultraviolet spectrum assuming subunit stoichiometry of 1:2:1:2
185000
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gel filtration
214200
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electrospray ionization mass spectroscopy
217100
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electrospray ionization mass spectroscopy
220000
286500
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electrospray ionization mass spectroscopy
310000
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calculated from the composition of subunits after gel filtration
additional information
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MW of products after cross linking glutaraldehyde
SUBUNITS
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
heterooligomer
homooctamer
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-
additional information
POSTTRANSLATIONAL MODIFICATION
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
acetylation
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N-terminus of Rieske iron-sulfur protein
glycolipoprotein
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-
Crystallization/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
vapour diffusion hanging drop method, X-ray structure at 3.1 A
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3.0 A crystal structure, native enzyme and enzyme in complex with 8-hydroxy-5,7-dimethoxy-3-methyl-2-tridecyl-4H-chromen-4-one or with 2,5-dibromo-5-methyl-6-isopropyl-benzoquinone
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free enzyme and enzyme complexed with with quinone analogue inhibitors tridecyl-stigmatellin and 2-nonyl-4-hydroxyquinoline N-oxide, X-ray diffraction structure determination at 2.70 A, 3.07 A, and 3.25 A resolution, respectively
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hanging drop vapour diffuion method, 0.0015 ml protein solution, containing 0.135-0.18 mM protein, is mixed with 0.0015 ml of reservoir solution, containing 100 mM Tris-HCl, pH 8.5, 200 mM MgCl2, 40 mM CdCl2, and 16?17% PEG-550 monomethyl ether, 4 C, hexagonal bipyramidal crystals appear in 24?36 h, X-ray diffraction structure determination at 2.8 A resolution
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hanging-drop vapor diffusion. A native structure of the cytochrome b6f complex with improved resolution is obtained from crystals of the complex grown in the presence of divalent cadmium
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hanging drop, vapor-diffusion method
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hanging drop vapour diffusion method using 1.5 M [NH4]2SO4, 100 mM sodium acetate at pH 4.6
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GENERAL STABILITY
ORGANISM
UNIPROT
LITERATURE
most stable in cholate buffer
-
mutant enzyme is more instable than wild type enzyme
-
PMSF prevents proteolysis during purification
-
STORAGE STABILITY
ORGANISM
UNIPROT
LITERATURE
-156C, best stability, or -80C or -20C
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-70C, 30 mM Tris-succinate buffer, pH 6.5, 1% sodium cholate, 10% glycerol
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0C, 4 days months
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0C, dark, 75% activity after 2 weeks
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22C, more than 1 week, complete loss of activity
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Purification/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
ammonium sulfate precipitation and hydroxyapatite column chromatography
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ammonium sulfate precipitation and sucrose gradient centrifugation
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five polypeptides
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metal ion affinity chromatography
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nickel-affinity resin chromatography and hydrophobic interaction chromatography
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partial purification from thylakoid membranes by ammonium sulfate precipitation and hydrophobic interaction chromatography
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plastoquinol and phospholipid deficient complex
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Rieske Fe-S protein
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Cloned/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
His6-tagged cytochrome f
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histidine tagged cytochrome f
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subunit IV
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ENGINEERING
ORGANISM
UNIPROT
COMMENTARY hide
LITERATURE
P194L
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mutation in the Rieske subunit of the cytochrome b6/f complex is characterized by a reduced electron transport activity at saturating light intensities in vivo. The electron transfer from cytochrome b6/f to photosystem I is not generally reduced in the mutant, but the pH dependence of the reaction is altered
E78D
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mutation in subunit IV, retained functional features of wild type configuration
E78L
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mutation in subunit IV, decrease in the rate of the concerted oxidation process at the Q0 site
E78N
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mutation in subunit IV, modified characteristics of cytochrome b6/f turnover under repetitive flash illumination
F40Y
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subunit IV mutation, in van der Waal's contact with the plane of ci heme
P2V
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different stigmatellin-sensitive reduction kinetics compared to wild-type enzyme
P2V/R156A
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different stigmatellin-sensitive reduction kinetics compared to wild-type enzyme
R156A
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different stigmatellin-sensitive reduction kinetics compared to wild-type enzyme
S154A
-
results in a 97 mV decrease in the midpoint potential relative to the wild-type and a 5fold decrease in sensitivity to inhibition by stigmatellin
S154C
-
results in a 17 mV increase in the midpoint potential relative to the wild-type
S154T
-
results in a 72 mV increase in the midpoint potential relative to the wild-type
Y156F
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results in a 45 mV decrease in the midpoint potential relative to the wild-type
Y156W
-
results in a decrease in the midpoint potential by 100 mV and substantial changes in the EPR spectra relative to the wild-type enzyme
A154G
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increased resistance to 2,5-dibromo-3-methyl-6-isopropylbenzoquinone and stigmatellin
D148G
-
sensitivity to myxothiazol
S159A
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increased resistance to 2,5-dibromo-3-methyl-6-isopropylbenzoquinone
F133L/F135L
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mutation on subunit IV, chlorophyll a binding niche
W125L
-
mutation on cytochrome b6, chlorophyll a binding niche
Y112F
-
mutation on cytochrome b6, chlorophyll a binding niche
additional information
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deletion of small domain of cytochrome f leads to changed kinetic parameters and faster degradation compared to the wild type enzyme
Renatured/COMMENTARY
ORGANISM
UNIPROT
LITERATURE
enzyme reacts with purified photosystem I reaction centers in the micellar state if plastocyanin is present; reconstitution into lipid vesicles
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reconstitution into lipid vesicles
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reconstitution into liposomes
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reconstitution of lipid- and plastoquinone depleted complex
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reconstitution of Rieske Fe-S protein into cytochrome b6-f complex
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reconstitution with lipids from spinach chloroplasts
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