Ch 18 Lecture 2
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What is bad about oxygen free radicals?
super radical; likes messing up DNA---> mutations
HOw does our body deal with them?
superoxide dismutase scavenges them and converts them to less reactive things, such as H2O2, which can be taken care of by catalase
What is special about cytC?
- same function; similar structure in many organisms
- changed very little over time
What is the end result of the ETC?
high concntration of H+ in space that wants to get in; this is the proton motive force
Why is the proton gradient necessary?
- It powers ATP synthase
- Though ATP production can still occur in the membrane, the release of the ATP can only be done in the presence of a proton gradient.
How did they test the ATP synthase and proton connection?
- Used bacteriorhodopsin and ATP synthase in a synthetic membrane
- Light-sensitive H+ pump allowed pumping of hydrogen ions, creating a proton gradient and powering ATP synthase, which produced ATP
Structure of ATP synthase? --> Part that stands still
has parts that stand still: subunits a and b, alpha and beta.
a and b are connected by a B2
a is two half channels that don't move. One opens to the space and one opens to the matrix
Structure of ATP synthase? --> Part that moves?
c ring: multisubunit ring of proteins; each subunit has 2 alpha helices connected by a loop; has a key aspartic acid in the center that acts as a proton acceptor
gamma: not uniform shape; apostrophe shaped in the interface between alpha and Beta subunits; point of contact changes as it spins around (counterclockwise), inducing a conformational change in the Beta subunit as it spins
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