ATP synthase - lecture 7 Flashcards
What is electron transfer coupled to?
Movement of protons across the membrane
Where does proton motive force build up?
Across the positive lumen side and negative stroma
What does proton motive force achieve?
Free energy available in the proton motive force drives the endergonic conversion of ADP to ATP by ATP synthase
Where is ATP and NADH generated from photosythesis used?
Calvin cycle
Which side of the membrane is acidic and basic?
Lumen side= acidic, Stroma side= basic
Which residue is protonated on a-subunit is protonated and why?
Arginine positively charged on a- subunit
Proximity of arginine to glutamate on carbon ring subunit reduces pKa of glutamate
Glutamate deprotonated and arginine protonated
Why is Glutamate protonated in the thylakoid membrane?
Glutamate protonated within hydrophobic membrane due to high pKa
Why is protonation allowed following deprotonation of glutamate?
High pmf allows glutamate to be protonated at a lower pKa
How does the C-ring rotate?
Attraction between negatively charged glutamate and positively charged arginine drives rotation
Is the gamma subunit connected to the alpha and beta?
No
Allows gamma to rotate 120 degrees with the carbon ring but not the alpha and beta “lollypop head”
Briefly describe how the beta subunits conformation changes and what is bound
Open conformation- ATP has been released and awaits ADP and Pi
Loose conformation- ADP and Pi bound
Tight conformation- ADP and Pi converted into ATP, ATP tightly bound
