CH 21: ATP synthase

Chemiosmotic theory

ATP is produced using the energy stored in a H+ gradient across a membrane

Gradiant = ATP production

Chemical + Electric Gradiant

Structure

2 parts

• F0 = Protein pump

  • Hydrophobic (phospholipids)

  • A6 = Helps connect Fo to F1

  • C-ring = H+ channel (from Mem to Mat)

• F1 = Catalytic (synthesis)

  • 5 polypeptide chains

  • 3x A (clover)

  • 3x B (clover)

  • y

  • E

  • 6

Binding Mechanism

• AB Complex Bind to Adp

• B can only synthesize it

• Rotation of Y: causes confirmational change in B

Binding mechanism: 3 Conformational sites

• O(open)= Bind/Release

  • ADP, Pi Binds at O

• L(Loose)= Holds ADP +PI

  • O→L traps substrates

• T(Tight)= Makes Atp from Adp and Pi (120*)

  • L→T Catalysis

  • T→ Release

C- Ring rotate

1. H+ enter Ims thru ½ Channel + Binds to Glutamate residue in C subunit

2. Protonated c subunits rotate thru the membrane (neutral)

3. In matrix H+ is released (High Ph luvs deprotonation)

4. Empty C-subunit Roates and binds to another H+

C-ring stoichiometry

C-Ring = 10-14 subunits

Protons = 1 Atp = 120*

Protons = 3 Atp = 360* (full Rotation)

Cytosolic NADH shuttles

NADH can’t cross Ims

Needs 2 shuttles:

• Glycerol - 3 Phosphate

  • Loc: Brain / Muscle

  • Fast = Less Atp (1.5 Atp)

  • NADH → FADH2 → Complex II

• Malate - Aspartate

  • Heart / Liver

  • Slow = Gives more ATP (2.5 ATP)

  • NADH → Malate → NADH in matrix → Complex I

Atp Yield (Per Glucose)

• Glycolysis: 2 ATP

• TCA: 2 ATP

= 4 ATP

Oxidative Phosphortylation

• 10 Nadh * 2,5 = 25 Atp

• 2 Fadh * 1.5 = 3 Atp

Total - 32 Atp

Uncoupling

• Ucp (natural) Dnp (Toxic)

  • Heat is used as energy

  • Ucp -1 no need for babies and animals to shiver.

ATP Synthase INHIBITORS

• Block flow from F0 → ETC stops (oligomyacin)

• To much H+ and cant pump back causes ETC chain to stop.

Exercise intese

Low Atp/Adp = we need to make more atp, high oxygen consumption

Acceptor Contro

No adp = No atp synthase = slow e- transport