MCB 2000 Lecture Notes - Lecture 26: Oligomycin, Rings Of Saturn, Electrochemical Potential

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Lecture 26 + 27
ETC Energy
Outline
E’0 reduction protential provides driving force for ATP synthesis
Flow of e- from MADH to O2 is exergonic (releases energy)
NET rxn There is an equation
ATP Synthesis + Mitchell’s Chemiosmotic Hypothesis
Proton gradient across inner membrane helps drive ATP synthesis
electrochemical
Differences in proton concentration
Differences in charge across inner mitochondrial membrane
Electrochemical potential: potential energy driving H+ to return to the matrix from the IM space
that ETC pumped it into
Energy stored in gradient is the pmf proton motive force
Conserves 200kJ per 2e-
Synthesis req 30kJ
As protons flow back into the matrix through proton pore
ATP synthase, pmf drives
synthesis + dissociation of ATP
Proton Pore
Proton diffusion through pore drives ATP synthesis
Draw this picture
2 segments: F0 and F1
F0 spans the membrane
F1 is in the matrix, protruding out
F0 is the pore, inhibition by oligomycin **********
ATP Synthase (F0F1 ATPase)
3 different conformations
L → ADP and Pi bind to LOOSE conformation
T → ADP + Pi converted to ATP, ATP bounds TIGHTLY
O → OPEN form, binds or releases
Proton enters the cytoplasmic half channel (subunit a), COO- is protonated, c ring rotates and the proton
exits matrix half channel and COO- is restored
C ring rotates clockwise, COO- is constantly being protonated in the a subunit and C ring rotates
to allow each COO- to be protonated, giving many protons being released into the matrix
Net yield of ATP from complete oxidation of glucose: 30 ATP
Electron Shuttles
Why: NADH produced by glycolysis cannot enter mitochondria by itself
Must enter through 2 shuttles
Malate-Aspartate (liver & heart)
Glycerol-3-phosphate (muscle)
Located on outer surface of inner membrane, FAD as prosthetic group
ATP from each NADH shuttled = 1.5 ATP
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Document Summary

E"0 reduction protential provides driving force for atp synthesis. Flow of e- from madh to o2 is exergonic (releases energy) Proton gradient across inner membrane helps drive atp synthesis. Differences in charge across inner mitochondrial membrane. Electrochemical potential: potential energy driving h+ to return to the matrix from the im space that etc pumped it into. Energy stored in gradient is the pmf proton motive force. As protons flow back into the matrix through proton pore atp synthase, pmf drives synthesis + dissociation of atp. Proton diffusion through pore drives atp synthesis. F1 is in the matrix, protruding out. F0 is the pore, inhibition by oligomycin ********** L adp and pi bind to loose conformation. T adp + pi converted to atp, atp bounds tightly. O open form, binds or releases. Proton enters the cytoplasmic half channel (subunit a), coo- is protonated, c ring rotates and the proton exits matrix half channel and coo- is restored.

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