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1. Structure of photosystem I at atomic resolution (PS I) 2. Function of PS I 3. Genetic analysis of structure-function relations 4. Two branches in electron transport in PS I 5. PS I a photo-nano-switch. PS I is a light driven plastocyanin ferredoxin oxidoreductase. - PowerPoint PPT Presentation
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1. Structure of photosystem I at atomic resolution (PS I)
2. Function of PS I
3. Genetic analysis of structure-function relations
4. Two branches in electron transport in PS I
5. PS I a photo-nano-switch
PS I is a light driven plastocyanin ferredoxin oxidoreductase.
Quantum efficiency for electron transfer is 1
PS I is part of the photosynthetic apparatus. A membrane protein chlorophyll complex one of the 4 complexes that make the transmembrane oxidoreductase system that oxidize water to O2 and reduces NADP+ to NADPH + H+, pump H+ that drive ATP synthesis.
PS I is part of the photosynthetic apparatus. A membrane protein chlorophyll complex one of the 4 complexes that make the transmembrane oxidoreductase system that oxidize water to O2 and reduces NADP+ to NADPH + H+, pump H+ that drive ATP synthesis.
Composition
12 subunits A-M, X (no H, G), 9 of them are transmembrane peptides. C, D & E are attached at the outside (storma).
M.W. 255 kDa
96 Chlorophylls, 22 carotenoids, 2 phylloquinons, 3 [4Fe4S] clusters.
Subunit arragem-ent view from stroma
FeSA/B
FeSX
Subunit C
Subunits A, B
The electron transfer chain is attached on subunits A, B & C.
P700, A0, A1, Fx, FA & FB.
P700- Chla dimer, parallel rings 3.5 A apart, perpendicular to the membrane, rings I, II partially overlap. Asymmetry: A branch has H bonds to H680 and to water. Lower spin density in the A ring of the radical P700+..
A0- Chla monomer (eC-A2, eC B2) has Mg-H-water-Asn591.
A1- phylloquinone, hydrophobic pocket LeuA722, TrpA697, TrpB673.
Two branches? QA-Fx 200ns, QB-Fx 20ns, B-branch is faster?
Fx,- 4Fe4S iron sulfur cluster, lowest potential in biology.
FA and FB- 4Fe4S iron sulfur clusters
FeSB
FeSA
FeSX
PQ
Ao (CHL)P700 (CHL2)
The electron transfer chain is attached on subunits A, B & C.
P700, A0, A1, Fx, FA & FB.
P700- Chla dimer, parallel rings 3.5 A apart, perpendicular to the membrane, rings I, II partially overlap. Asymmetry: A branch has H bonds to H680 and to water. Lower spin density in the A ring of the radical P700+..
A0- Chla monomer (eC-A2, eC B2) has Mg-H-water-Asn591.
A1- phylloquinone, hydrophobic pocket LeuA722, TrpA697, TrpB673.
Two branches? QA-Fx 200ns, QB-Fx 20ns, B-branch is faster?
Fx,- 4Fe4S iron sulfur cluster, lowest potential in biology.
FA and FB- 4Fe4S iron sulfur clusters
The electron transfer chain is attached on subunits A, B & C.
P700, A0, A1, Fx, FA & FB.
P700- Chla dimer, parallel rings 3.5 A apart, perpendicular to the membrane, rings I, II partially overlap. Asymmetry: A branch has H bonds to H680 and to water. Lower spin density in the A ring of the radical P700+..
A0- Chla monomer (eC-A2, eC B2) has Mg-H-water-Asn591.
A1- phylloquinone, hydrophobic pocket LeuA722, TrpA697, TrpB673.
Two branches? QA-Fx 200ns, QB-Fx 20ns, B-branch is faster?
Fx,- 4Fe4S iron sulfur cluster, lowest potential in biology.
FA and FB- 4Fe4S iron sulfur clusters
The electron transfer chain is attached on subunits A, B & C.
P700, A0, A1, Fx, FA & FB.
P700- Chla dimer, parallel rings 3.5 A apart, perpendicular to the membrane, rings I, II partially overlap. Asymmetry: A branch has H bonds to H680 and to water. Lower spin density in the A ring of the radical P700+..
A0- Chla monomer (eC-A2, eC B2) has Mg-H-water-Asn591.
A1- phylloquinone, hydrophobic pocket LeuA722, TrpA697, TrpB673.
Two branches? QA-Fx 200ns, QB-Fx 20ns, B-branch is faster?
Fx,- 4Fe4S iron sulfur cluster, lowest potential in biology.
FA and FB- 4Fe4S iron sulfur clusters
