Oxidative Phosphorylation

Part 1of Three

Chapter 19

Oxidative Phosphorylation Part 1

– Electron-transport chain in mitochondria– Redox calculations– E-transport inhibitors– Building up the proton-motive force

Key topics: To Know

EOC Problem 1 is all about recognizing electron donors and acceptors…a quick review to make the rest of the chapter easy.

Mitochondria Review

Chapters: 16,17,18

Chapter 19

SEM of Mitochondia

Mitochondia in Heart and Liver

Attempts to show more inner membrane structure in heart mitochondria compared to

liver mitochondria.

Dehydrogenases in Cytoplasm and Mitochondria

Quinones – 1 and 2 electron carriers

EOC Problem 2 looks at the ubiquinone parts and their functions. Note the isoprene length.

Cytochromes One Electron Carrier

Cytochromes Easily Measured by Spectrophotometry

Difference Spectrum Vibrio harveyi. Taken from: Guerrero and Makemson 1989 Current Microbiology 18:67-73

Difference Spectrum (Reduced – Oxidized)

Iron Sulfur Protein Models

Electron Transport Carriers Redox Tower

Electron Carrier Sequence Determined from Inhibitors

Electron Transport Inhibitors

Isolation of Complexes

from Mitochondria

Electron Carriers Arranged in Modules (Complexes)

Entry Points to Electron Transport

EOC Problem 3: why is it that Succinate has to use FAD rather than NAD+?

Complex I

Complex I Structure is Solved

Efremov, RG et al., May, 2010 Nature 465:441-445

in cytoplasmic membrane

Cytoplasm

Periplasm

Is this from mitochondria or bacteria?

Complex I WorkingH+ H+ H+ H+

Complex II

Entry Points to Electron Transport

Complex III

Complex IV

Complex IV : Proton Pumping/Oxygen Reduction

Yeast Complex III and IV

Respirasome

TEM (whole, Uranyl Acetate) Superimpose Xray Structures Composite of 100’s of Images

Complex IV Complex III green red

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 IV1NADH + 11H+

(N) + ½O2 ——> NAD+ + 10H+

(P) + H2O

Complex II Complex IVFADH2 + 6H+

(N) + ½O2 ——> FAD + 6H+

(P) + H2O

Difference in number of protons transported reflects differences in ATP synthesized.

Complex 1,3,4 or

2,3,4

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

1. Where the DH’s are.

2. The electron transport players: flavin, Fe-S centers, cytochromes (and their properties), quinones, Cu++.

3. Is it the ABCs of electron transport or the BCAs?

4. Effects of electron transport inhibitors.

5. Entry points and what each complex does.

6. How to calculate ΔGo’ from ΔEo’.

7. EOC Problems: 1-5.