1. Chapter 10
Chem 341
Suroviec Fall 2016

2. I. Introduction
Redox reaction that releases electrons into mitochondrial electron transport chain
Mitochondrial electron-transport chain
Electrons transferred to other substances to participate in additional oxidation rxns
Transferred electrons participate in sequential redox reactions of multiple redox centers in 4 enzyme complexes
During electron transfer protons are expelled making a proton gradient

3. A. Mitochondrial Anatomy
Contains
Pyruvate dehydrogenase
CAC enzymes
Enzymes and redox proteins for electron transport and oxidative phosphorylation
B. Mitochondrial Transport
Outer membrane contains proteins allows diffusion of proteins
Intermembrane space equivalent to cytosol

4. 1. Cytosolic Reducing Equivalents
NADH produced in cytocol must gain access into mitochodrial electron transport chain
Inner membrane does not have NADH transport protein
Only the electrons from cytosolic NADH are transported

5. II. Electron Transport
In a redox reaction there are electrons transferred
Reduction Potentials
Indicates a substance’s ability to accept electrons

6. Example
Calculate the reduction potential of substance A when E = 0.5V, [Ared] = 5 x 10-6M, [Aox] = 2 x 10-4M and n = 2

7. B. Free Energy Change
DG can be calculated from Eo’
electrons flow spontaneously from substance with lower Eo’ to higher Eo’
Example
In yeast, alcohol dehydrogenase reduces acetaldehyde to ethanol. Find DGo’

8. B. Sequence of Electron Transport
Oxidation of NADH and FADH2 is carried out by electron transport chain
Set of protein complexes containing redox centers with progressively greater affinities for electrons

10. 1. Complex I
Passes electrons from NADH to CoQ
Contain FMN
Contain iron – sulfur clusters

11. 2. Complex II
Contains succinate dehydrogenase
Passes electrons from succinate to CoQ

12. 3. Complex III
Passes electrons from reduced CoQ to cytochrome c

13. Q - Cycle
In complex III need to transport 1 electron at a time from CoQ through cytochromes

14. 4. Complex IV
Catalyzes one electron oxidation of 4 consecutive reduced cytochrome c molecules
Reduces oxygen

15. Inhibitors of electron transport

16. III. Oxidative Phosphorylation
Chemiosmosis
Free energy of electron transport is conserved by pumping H+ from matrix to intermembrane space
Gradient makes ATP synthesis possible

17. Binding change mechanism
B. ATP synthase
Multisubunit: F1 and F0
Binding change mechanism

18. IV. Control of Oxidative Phosphorylation
Concentrations of intermediates and energy currency turn on/off oxidative phosphorlyation