Flashcards in Lecture 8: ATP synthesis Deck (18)
What are the two parts of ATPsynthase called?
F1 and F0
What are the component parts of F1?
Which subunit binds F1 and F0 together?
Which subunit contains the catalytic site for ATP?
What are the component parts of F0?
Three transmembrane subunits: a, b and c. They form an a1b2c9-10 (9 or 10 c parts dependent on species).
F0 also contains a, F6 and OSCP (antibiotics can kill bacteria by targeting this). The c subunits form a ring.
Where is F1 situated and how does its composition suit this?
F1 is situated in the matrix and is water soluble as a result of being made up of hydrophilic polypeptides.
Where is F0 situated and how does its composition suit this?
F0 is situated in the inner mitochondrial matrix and is hydrophobic.
Describe the mechanism of ATP synthesis in 3 phases.
1) Translocation of H+s carried out by F0
2) Catalysis of formation of the phosphoanhydride bond of ATP carried out by F1
3) Coupling of the dissipation of the proton gradient with ATP synthesis, which requires interaction of F1 and F0.
Which conformational shapes can the 3 protomers of the F1 exist in?
L, O and T
L = binds substrates/products loosely
O = does not bind anything
T = binds substrates/products tightly
How do the protomers change conformation?
The energy stored in the electrochemical proton gradient is released when the protons are translocated into the matrix and is used to inter-convert these conformations.
What is significant about the T conformation?
When ADP and Pi are in a protomer with the T conformation (tightly bound), minimum energy is required to synthesise the phosphoanhydride bond and make ATP.
What happens to the ATP in the T protomer once it has been synthesised?
When the conformations change again, that protomer will take on the O conformation and ATP will be released.
What is a stator?
It is the stationary part which a rotor is rotating with respect to.
Which component parts make up the rotor in ATPsynthase?
Gamma, Epsilon- c12 ring complex
Which component parts make up the stator in ATPsynthase?
What causes the rotational movement of the rotor?
The passage of protons from the outside to the inside.
What prevents the alpha3-beta3 assembly from rotating with the gamma subunit?
The b2-delta complex