Principles of Biochemistry 4e

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• Chapter 14 Electron Transfer and
• Oxidative Phosphorylation, Part 1.
• Overview.
• The mitochondrion revisited
• The mitochondrial electron transport
• chain.
• 4. More electron carriers.

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• Overview
• Where are we?
• We started with glucose
• A) Lost 6 CO2
• B) Made 4 ATP
• C) Energy rich electrons.
• 10 NADH
• 2 FADH2

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• What do we do with all of the energy-
• rich electrons?
• Electron transport
• Hydrogen ion transport
• ATP formation

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2. The mitochondrion revisited.
Electron transport, H ion transport ATP
formation occur in the inner membrane.
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Schematic of the inner mitochondrial membrane.
Complex ATP
I III IV synthase
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ATP synthase
Inner mitochondrial membrane
I
III
IV
Q
Cyt c
II
O2
Looking down on it.
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Small electron carriers shuttle electrons
between the complexes.
Coenzyme Q CoQ, Q
Cytochrome c (Cyt c)
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Release energy
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The relationship between potential drop and free
energy changes.
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• More electron carriers.
• A) Coenzyme Q
• B) Iron sulfur proteins (FeS)
• C) Cytochromes

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• Coenzyme Q (CoQ)
• Ubiquinone.

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2e- -2e- 2H 2H
2
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B) FeS proteins 1 electron No protons
Fe3 1e- ? Fe2
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C) Cytochromes
a,b,c
Protoporphyrin IX
Fe3 1e- ? Fe2
Know the porphyrin ring
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Eo
0.23 0.08 0.29
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Intermembrane space
Complex I
matrix
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