Chapter 19 Oxidative Phosphorylation Part 1 of Three
Oxidative Phosphorylation Part 1 Key topics: To Know • Electron-transport chain in mitochondria • Redox calculations • E-transport inhibitors • Building up the proton-motive force EOC Problem 1 is all about recognizing electron donors and acceptors…a quick review to make the rest of the chapter easy.
Mitochondria Review Chapter 19 Chapters: 16,17,18
Mitochondia in Heart and Liver Attempts to show more inner membrane structure in heart mitochondria compared to liver mitochondria.
Quinones – 1 and 2 electron carriers EOC Problem 2 looks at the ubiquinone parts and their functions. Note the isoprene length.
Difference Spectrum (Reduced – Oxidized) Difference Spectrum Vibrio harveyi. Taken from: Guerrero and Makemson 1989 Current Microbiology 18:67-73
Entry Points to Electron Transport EOC Problem 3: why is it that Succinate has to use FAD rather than NAD+?
Complex I Structure is Solved Periplasm in cytoplasmic membrane Cytoplasm Is this from mitochondria or bacteria? Efremov, RG et al., May, 2010 Nature 465:441-445
Complex I Working H+ H+ H+ H+
Yeast Complex III and IV Respirasome Complex IV Complex III green red TEM (whole, Uranyl Acetate) Superimpose Xray Structures Composite of 100’s of Images
Electron Transport Summary EOC Problems 4 and 5 examine aspects of electron transfer and amounts of oxygen, NAD+, and other things such as inhibitors…great problems !
Summary of Electron Transport Complex I Complex IV 1NADH + 11H+(N) + ½O2 ——> NAD+ + 10H+(P)+ H2O Complex II Complex IV FADH2+ 6H+(N) + ½O2 ——> FAD + 6H+(P) + H2O Difference in number of protons transported reflects differences in ATP synthesized.
Calculations Differences between half cells…Example of electron transfer from NADH to ubiquinone (going from NADH through Complex I to ubiquinone): NADH Eo’ = -.32 v Ubiquinone Eo’ = 0.045 v ΔEo’ =Eo’oxidized – Eo’ reduced = 0.045v – (-0.32v) ΔEo’ = 0.365 v
ΔG’o Calculation What is the ΔG’o for oxidation of NADH by ubiquinone ΔG’o = - nƑΔEo’ Faraday Constant = 96,480 J/v.mole = 96.5 kJ/v.mole ΔG’o = - (2) 96.5 kJ/v.mole (0.365v) = - 70.4 kJ/mole How Many “ATPs” is this worth?
Things to Know and Do Before Class • Where the DH’s are. • The electron transport players: flavin, Fe-S centers, cytochromes (and their properties), quinones, Cu++. • Is it the ABCs of electron transport or the BCAs? • Effects of electron transport inhibitors. • Entry points and what each complex does. • How to calculate ΔGo’ from ΔEo’. • EOC Problems: 1-5.