OXIDATION PHOSPHORYLATION1

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BIOC 460 - DR. TISCHLER LECTURE 28
OXIDATION PHOSPHORYLATION-1
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OBJECTIVES

• Reduction potential differences (?Eo) general
  relationship between ?Eo and the free energy
  difference ?Go
• Essential features of oxidative phosphorylation
  and the role of redox reactions in the e-
  transport (respiratory) chain
• For the respiratory chain major complexes (I to
  IV)
• a) identify by name
• b) components that donate electrons to
  and accept electrons
• c) prosthetic groups important in the
  electron transfer
• d) explain how energy from complexes is
  conserved and which ones produce sufficient
  energy to make ATP.

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REDUCTION-OXIDATION REACTIONS
Oxidative portion of oxidative phosphorylation
redox reactions Phosphorylation portion is ADP
Pi ? ATP Two half reactions Reductant1 ?
Oxidant1 e- Oxidant2 e- ? Reductant2
Overall reaction Reductant1 Oxidant2 ?
Reductant2 Oxidant1 Redox reactions are
exergonic because ?Go is negative ?Go -nF?Eo
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O2
e-
ADPPi
outer membrane
inner membrane
H2O
ATP
H
H
intermembrane space
matrix
Figure 1. Essential features of oxidative
phosphorylation. redox reactions of respiratory
chain use electrons to reduce oxygen to
water energy generated moves protons from matrix
to intermembrane space inward movement of protons
recovers this energy to promote formation of ATP
in the matrix.
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?Eo' 0.07V
?Eo' 0.19V
?Eo' 0.53V
?Eo' 0.42V
Figure 2. Overview of the respiratory chain
showing the progression of reduction potentials
from strong to weak reductants culminating in
oxygen as the ultimate electron acceptor. The
?Eo? values are the potential differences across
the four complexes
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Table 1. Summary of the redox complexes of the
electron transport chain
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Figure 3. Complex I of the respiratory chain
that links NADH and coenzyme Q. DH is NADH
dehydrogenase.
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Figure 4. Complex II of the respiratory chain.
SDH is succinic dehydrogenase an enzyme of the
citric acid cycle.
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Figure 5. Complex III of the respiratory chain
linking CoQ and cytochrome C.
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Figure 6. Complexes III and IV linked by
cytochrome C with complex IV reducing oxygen to
water.