1. Electron Transport and Oxidative Phosphorylation It all reduces down to water.

2. Mitochondria outer membrane relatively permeable inner membrane permeable only to those things with specific transporters –Impermeable to NADH and FADH 2 –Permeable to pyruvate Compartmentalization –Kreb's and β-oxidation in matrix –Glycolysis in cytosol

3. Most energy from Redox electrons during metabolic reactions sent to NAD and FAD –Glycolysis In cytosol produces 2 NADH –Pyruvate dehydrogenase reaction In mitochondrial matrix 2 NADH / glucose –Krebs In mitochondrial matrix 6 NADH and 2 FADH 2 / glucose

4. Electron Transport Chain Groups of redox proteins –On inner mitochondrial membrane –Binding sites for NADH and FADH 2 On matrix side of membrane Electrons transferred to redox proteins NADH reoxidized to NAD + FADH 2 reoxidized to FAD

5. 4 Complexes proteins in specific order Transfers 2 electrons in specific order –Proteins localized in complexes Embedded in membrane Ease of electron transfer –Electrons ultimately reduce oxygen to water 2 H + + 2 e - + ½ O 2 --  H 2 O

6. Electron Transport Chain

7. Complex 1 Has NADH binding site –NADH reductase activity NADH -  NAD + –NADH ---> FMN--->FeS---> ubiquinone –ubiquinone ---> ubiquinone H 2 –4 H + pumped/NADH

8. Electron Transport Chain

9. Complex II succinate ---FAD—ubiquinone –Contains coenzyme Q –FADH 2 binding site FAD reductase activity FADH 2 --  FAD

10. Electron Transport Chain

11. Complex III ubiquinone -  ubiquinone ox while cyt C gets reduced Also contains cytochromes b –proton pump 4H + Adds to gradient 8 H + / NADH 4 H + / FADH 2

12. Electron Transport Chain

13. Complex IV reduction of oxygen cytochrome oxidase cyt a+a3 red ---> oxidized state oxygen ---> water –2 H + + 2 e - + ½ O 2 --  2 H 2 O –transfers e - one at a time to oxygen Pumps 2H + out –Total of 10 H + / NADH –Total of 6 H + / FADH 2

14. Totals Proton gradient created as electrons transferred to oxygen forming water 10 H + / NADH 6 H + / FADH 2

15. Electron Transport Chain

16. Generation of ATP Proton dependant ATP synthetase –Uses proton gradient to make ATP –Protons pumped through channel on enzyme From intermembrane space into matrix ~4 H + / ATP –Called chemiosmotic theory

17. Totals NADH 10 H + X 1 ATP = 2.5 ATP 4 H + FADH 2 6 H + X 1 ATP = 1.5 ATP 4 H +

18. Total ATP from mitochondrial matrix Pyruvate dehydrogenase –NADH ……………………………….2.5 ATP Krebs 3 NADH X 2.5 ATP/NADH ……….7.5 ATP FADH 2 X 1.5 ATP / FADH 2 ……….1.5 ATP GTP X 1 ATP / GTP ……………..1.0 ATP (from a separate reaction) Total…………….12.5 ATP (Per glucose = X 2 = 25 ATP)

19. What about NADH from glycolysis? NADH made in cytosol Can’t get into matrix of mitochondrion 2 mechanisms –In muscle and brain Glycerol phosphate shuttle – In liver and heart Malate / aspartate shuttle

20. Glycerol Phosphate shuttle http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-3/ch19_glycerol-shuttle.jpg

21. Glycerol phosphate shuttle In muscle and brain Each NADH converted to FADH 2 inside mitochondrion –FADH 2 enters later in the electron transport chain –Produces 1.5 ATP

22. Total ATP per glucose in muscle and brain Gycerol phosphate shuttle –2 NADH per glucose -  2 FADH 2 –2 FADH 2 X 1.5 ATP / FADH 2 ……….3.0 ATP –2 ATP in glycoysis……………………2.0 ATP –From pyruvate and Krebs 12.5 ATP X 2 per glucose ……………..25.0 ATP Total = 30.0 ATP/ glucose

23. Malate – Aspartate Shuttle http://courses.cm.utexas.edu/emarcotte/ch339k/fall2005/Lecture-Ch19-2/Slide14.JPG

24. Malate – Aspartate Shuttle in cytosol In liver and heart NADH oxidized while reducing oxaloacetate to malate –Malate dehydrogenase Malate crosses membrane

25. Malate – Aspartate Shuttle in matrix Malate reoxidized to oxaloacetate –Malate dehydrogenase –NAD + reduced to NADH NADH via electron transport yields 2.5 ATP Mlate – Aspartate Shuttle in cytosol

26. Total ATP per glucose in liver and heart Malate – Aspartate Shuttle –2 NADH per glucose -  2 NADH –2 NADH X 2.5 ATP / NADH…………5.0 ATP –2 ATP from glycolysis………………..2.0 ATP –From pyruvate and Krebs 12.5 ATP X 2 per glucose ……………..25.0 ATP Total = 32.0 ATP/ glucose

27. Summary Total ATP / glucose –Muscle and brain30.0 ATP Uses glycerol phosphate shuttle –Heart and liver32.0 ATP Uses malate aspartate shuttle