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What’s new in this book’s presentation of respiration?What’s confusing?
How many proteins are involved?What are their roles?
Which metalloproteins have their own names?
What are the essentials of chemiosmosis?
What molecule is responsible for creating the H+ gradient?
What are the two requirements of chemiosmotic hypothesis?
How many and which metals are involved in respiration?In what types of centers are these metals in?
What is the reaction that provides the energy for ATP formation?
matrix
cytosol
Cyt c
c1
c
2 x QH2
QH2
2 Q
Q
Complex III – creates H+ gradient
H+‘s are pulled in from inside for Q redn
H+ ‘s are
released
outside for
QH2 redn
Fe(II) Fe(III)
Complex IV – Cytochrome C Oxidase
Cu(II) Cu(I)
Cu(II)—Cu(I) Cu(I)—Cu(I)
oxy
peroxy
Ferryl
oxidized
reduced
H+ limiting
H+ limiting
Complex IV – Cytochrome C Oxidase
– H2O
O-O2-
– H2O
START
Internal redox
Ubiquinone
Stigmatellin - co-crystallized in Cyt B1C
The magical partnership of Metal and organic redox
Photosystem I
SUN CATCHER Each lobe of clover-leaf-shaped crystal of photosystem I contains 12 different proteins,
shown here in different colors with only the protein backbone of each depicted. Amid the proteins are 96 chlorophylls (pale yellow) as well as other cofactors.
Photosystem I
How do chl molecules behave as attennae?
Inside thylakoid:4 H+ produced here
Outside thylakoid:4 H+ lost from here
carboxylation
regeneration
reduction
What are the two processes in PS and what are their names?
What is the OEC?
Inside thylakoid:4 H+ accumulates here
Outside thylakoid:4 H+ lost from here
carboxylation
regeneration
reduction
Net ET reaction: H2O PSII plastoQ cyt b6f plastocyanin PSI Fe2S2 NADP+
“Z-Scheme” How is the energy of light converted into
chemical energy in the 1st step?
How many and which metals are involved in
PS?
Mn4O4 cluster in PSIIparallels Complex I in respiration
Plastocyanin in PSIparallels cyt c in respiration
PSI parallels Complex IV= cyt c oxidase in respiration
+ 4e-
Eox (V)
+1.2 V
+0.6 V
0.0
-0.6 V
-1.2 V
What are the similarities and differences between
respiration and photosynthesis?
1. Cristae and thylakoid: inner membrane structures2. Cyt bd in mitochondria ~ cyt b6f in chloroplasts
3. Small organic electron/proton carriers4. Multi-metal site for multi electron processes5. Reactive centers embedded in membranes
6. Creation of proton gradient7. PSII reduces a Q to QH2; PSI is like complex IV
8. Plastocyanin functions like Cyt c9. Use of aa residue as radical (Tyr)
PSII @ 3.5 Å resolution
Cytochorme b6f (analog of respiratory cytochrome b1c)
PSI Reaction Centercofactors only
PSI Reaction Center
Chlpigments
E-acceptor