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