ATP synthase Flashcards
Who proposed the chemiosmotic model?
Mitchell
What did the chemiosmotic model proposed?
PMF conserves energy of electron transfer and drives ATP synthesis as protons flow back into mm via proton pore Fo in inner mm.
What is needed to produce ATP?
ADP, Pi and succinate.
What are the 2 coupled reactions of ATP synthesis?
ATP synthesis and O2 production.
What blocks the electron transport and stops O2 consumption and ATP synthesis?
Cyanide.
What reagents mimic proton influx/efflux?
DNP
What did the chemiosmotic model show?
That e-transfer, OMF and ATP synthesis are obligately coupled.
What do inhibitors of the electron transport block?
ATP synthesis.
What do inhibitors of ATP synthesis block?
Electron transport
Which scientist worked out how PMF causes enzyme ATP synthase to synthesise ATP?
Walker
What do the ATP synthase complexes in the mitochondria make?
The ATP required to sustain life by a rotary mechanism.
ATP synthase enzyme is what type of enzyme and how many distinct functional domains does it have?
F-type ATPase purificed and crystallised has 2 distinct functional domains F1 and F0
What is human ATP synthase assembled from?
27 nuclear encoded genes and two mitcondrondrially encoded genes.
What type of protein is F1?
It is a peripheral membrane protein - is hydrophilic.
Which side is the F1 protein on ?
The N side - negative side, it is attached to inner mitochondrial membrane.
Which protein F1 or F2 is the catalytic domain - where ATP is synthesised.
F1
What type of protein is F0?
It is an integral membrane protein - hydrophobic.
Spans the mitochondrial inner membrane proton pore?
In F0, what takes place?
The H+ move through it against conc gradient from intermembrane space through F1 to matrix - this proton flow enables ATP synthesis.
Describe the F1 structure?
9 subunits - 5 different types.
A3, B3, y, delta, epsilon
A and B alternate around the central y shaft.
A and B have binding sites
Which are the more important subunits in the F1 structure?
The Beta subunits - can bind ADP, ATP or be empty
Which protein makes up the proton pore?
The integral F0 protein.
Which subunits is F0 composed of?
ab2cn
Which is the more important subunits in F0?
C subunits - clindar like structure with pore number of C subunits difference b/w species 8-15
What do the C subunits in F0 do?
They rotate together around a perpendicular axis - around epsilon and gamma which ‘stand’ on C subunits.
Which protein was purified first?
F1 - could only synthesis ATP when F0 was added.
What components are needed for ATP synthase to work?
F0 - bind ATP and ADP + Pi = synthesise ATP
F1 = ATP bound tightly and that proton energy needed to ‘dislodge’ it.
Which direction does proton energy flow through?
F0 to F1
What did Boyer propose?
That the binding change mechanism to explain how ATP synthase synthesises ATP.
What causes the F1 to rotate?
When protons pass through F0 and cause cylinder of c units attacked to gamme (subunit of F1 to rotate about long axis of gamma)
Which subunits rotates?
The y subunits and passes through the centre of alpha 3 and beta 3 which are stationary
Which catalysis causes ATP synthesis?
Rotational
Which subunits are the ATP and ADP bound to?Which is more tightly bound?
Beta subunits, ATP is more tightly bound
ADP also has Pi
Which subunit rotates and comes into contact with each beta subunit in succession?
gamma
How many protons induce a rotation and what is the degree of rotation? How many ATP are formed?
3 protons induce a rotation of 120 degrees. 1 ATP formed
How many conformations and ATPs are syntehsised in a full rotation?
360 degree = beta gone through 3 conformations and 3 ATP synthesised.
Can the ATP synthase work in reverse?
Yes, in ATPase breaking down.
Which type of microscopy enabled visualisation of the gamma subunit rotating due to proton flux through F0 cylinder of C subunits.
Atomic Force Microscopy
How is OXPHOS regulated?
Regulation of enzymes in glycolysis, fat catabolism, citric acid cycle and OXPHOS integrated to maintain constant ratio of ATP/ADP(Pi)
What affects the regulation og OXPHOS?
The energy needs of the cell/tissue & organism.
Can become impaired in aging
