ATP synthesis Flashcards
What is another name for ATP Synthase
F0F1 complex
What does the F0 complex do and what is it made of
F0 is composed of roughly 14 integral membrane proteins forming the base and the peripheral stalk of the ATP synthase: 8-15 c subunits, one a subunit and two b subunits.
Acts as proton “turbine”
N side = mitochondrial matirx
P side = intermembrane space
What does the F1 complex do and what is it made of
F1 is composed of 5 proteins, designated α (alpha), β (beta), δ (delta), ε (epsilon) and γ (gamma), forming the knob and the central stalk.
(αβ)3 γ, δ and ε
ATP synthase activity
N side = mitochondrial matirx
P side = intermembrane space
What is the binding-change model
Rotation of the γ subunit, driven by the passage of protons through channels in F0, cause sequential conformational changes in the three αβ dimer assemblies that alter their substrate-binding abilities.
The turbine contains a
1) Rotor
2)Stator
What is a rotor
Rotating (non-stationary) part of a motor or turbine.
What is a stator
Stationary part of a motor or turbine.
What subunits of the AtP synthase complex is a rotor (moving)?
c-ring, δ, ε and γ.
What subunits of the ATP synthase complex is a stator (stationary)
a, b and the 3 αβ dimers
Explain the flow of protons in the ATP synthase
- Enters a channel which spans half the length of subunit a.
- These protons bind and drive the rotation of the c-ring (one proton for each c subunit)
- The turning triggers δ, ε and γ to turn and cause a confirmational change in the 3 αβ dimers
- Protons exit in the mitochondrial matrix by a second channel on subunit a.
Which structure is key to ATP synthase and triggers confirmational changes in the 3 αβ dimers
The gamma subunit
What is the consequence if one of the 2 gamma (y) subunits is removed
The turn will cause different contacts as the second y subunit turns and makes contact with the alpha-beta dimer. The y subunit causes a change in the confirmation of the alpha-beta subunit turns. So if the one y subunit is removed, there will be a decrease in ATP synthesis because the alpha-beta subunit will not be able to change confirmation to generate ATP as there will only be one y subunit turning around (it is the asymmetric portion of the gamma (y) subunit)
Describe the strucutre of the 3 αβ dimers
of the ATP synthase
3 αβ dimers
3 catalytic sites
αβ dimer conformations:
O: Open (Empty)
L: Loose binding to ADP
T: Tight binding to ATP
Describe how the confirmational change of the 3 αβ dimers works
Conformation sequence
O ->L -> T
-ADP + Pi binds to the catalytic site in L conformation
-ATP is formed when the catalytic site is in T conformation.
-ATP is released when the conformation passes from T to O
how many protons are pumped out of for NADH in the e- transport chain
10
how many protons are pumped out for FADH2 in the e- transport chain
6
how many protons are needed to generate 1 ATP
4 (1 used to transport Pi into the matrix and 3 to drive the ATP synthase)
how many protons are needed to generate 1 ATP
4 (1 used to transport Pi into the matrix and 3 to drive the ATP synthase)
How much ATP does 1 NADH generate
2.5 ATP
How much ATP does FADH2 generate
1.5 ATP
Explain the phosphate oxygen ratio
One electron pair reduces one atom of oxygen to produce H2O, then the number of ATP molecules produced per atom of oxygen that is reduced is:
2.5 for NADH
1.5 for FADH2
T or F: the inner mitochondrial membrane is permeable to NADH
False, NADH must be carried through the membrane via a carrier
What are the 2 carrier mechanisms for transport of ATP into the mitochondria
- Malate-aspartate shuttle
2.Glycerol-3-phosphate
What are the 6 steps of the malate aspartate shuttle to bring NADH into the mitochondria
- Reduction of oxaloacetate into malate by the malate dehydrogenase using the reducing equivalent from NADH.
- Transport of malate into the mitochondria matrix by the malate-α-ketoglutarate transporter
- Oxidation of malate into oxaloacetate by the malate dehydrogenase transferring reducing equivalent to NAD+.
- Transamination of oxaloacetate into aspartate by the aspartate aminotransferase(transaminase).
- Transport of aspartate outside of the mitochondria matrix by the glutamate-aspartate transporter.
- Transamination of aspartate into oxaloacetate by the aspartate aminotransferase (transaminase). (same reaction as 4 just backwards)
What happens in reaction 4 of the malate aspartate shuttle
Just exchaning amino and ketone group
T or F: the malate aspartate shuttle for transporting NADH into the mitochondria is through gluconeogenesis
False, its triggered for glycolysis, in gluconeogenesis NADH is transferred out of the mitochondria
T or F: the malate aspartate shuttle for transporting NADH into the mitochondria is through gluconeogenesis
False, its triggered for glycolysis, in gluconeogenesis NADH is transferred out of the mitochondria
What are the 4 steps of the glycerol-3-phosphate shuttle
- Dihydroxyacetone phosphate (DHAP) is reduced to glycerol-3 phosphate by the cytosolic glycerol 3-phosphate dehydrogenase using electrons equivalents from NADH
2.Glycerol-3 phosphate enters the mitochondrial intermembrane space
- Glycerol-3 phosphate is re-oxidizes into Dihydroxyacetone phosphate (DHAP) by the mitochondrial glycerol 3-phosphate dehydrogenase
- Electrons are stored on FAD (which is linked to the enzyme) and then, transferred to ubiquinone (Q) to form QH2.
NOTE: This shuttle mechanism bypasses complex I and II of the ETC (losing 4 protons = 1ATP)
The malate aspartate shuttle is mainly used in
liver, kidney, and heart mitochondria
The glycerol-3-phjosphate shuttle is used in the
skeletal muscle and brain
Name the steps of the glycerol-3-phosphate shuttle
- Dihydroxyacetone phosphate (DHAP) is reduced to glycerol-3 phosphate by the cytosolic glycerol 3-phosphate dehydrogenase using electrons equivalents from NADH
- Glycerol-3 phosphate enters the mitochondrial intermembrane space
- Glycerol-3 phosphate is re-oxidizes into Dihydroxyacetone phosphate (DHAP) by the mitochondrial glycerol 3-phosphate dehydrogenase
- Electrons are stored on FAD (which is linked to the enzyme) and then, transferred to ubiquinone (Q) to form QH2.
NOTE: This shuttle mechanism bypasses complex I and II of the ETC (losing 4 protons = 1ATP)
