Download Pumps protons across the cytoplasmic membrane

Chapter 9: Photophosphorylation
Capture energy from sunlight
Simple systems such as bacteriorhodpsin, may have been
the first to create charge separating membranes,
possibly predating respirative electron transport
Basic Idea:
Ground state
hn, photon
Excited state
Not unlike redox reactions
A More Useful Rxn
hn, photon
Ground state
Excited state
ADP + P  ATP
OR
NADP+ + e-  NADPH
Photosystems in Order of Likely Evolutionary Appearance
1.)
2.)
Anoxygenic, no O2 produced
OR
Bacteriorhodopsin-like
Oxygenic, leading to the production of O2, requires larger
energy gaps and more reactions
Bacteriorhodopsin-like:
--- Conformational cycling of a protein-carotenoid pair
--- Driven by carotenoid photon absorption
--- Pumps protons across the cytoplasmic membrane
--- pmf drives ATP synthase
--- A one protein light driven proton pump
Light Driven Confromational Cycling in Carotenoid
pigment of Bacteriorhodopsin
--- Shift’s Base Reaction
Light Driven Rxn
More Complicated Schemes
Anoxygenic Photosynthesis
Purple Non-Sulfur Bacteria
Purple Sulfur Bacteria
Green Sulfur Bacteria
Another Delocalized p system: Bacteriochlorophyll
The Advantage of Chlorophyll:
Molecule to Molecule Energy Transfer
Cyanobacterial Photosynthesis
Racker Experiment