The document summarizes oxidative phosphorylation and the electron transport chain. It describes how electrons from NADH and FADH2 are transferred through four complexes embedded in the inner mitochondrial membrane and used to pump protons out of the matrix. The complexes use prosthetic groups like heme and Fe-S centers. The electron transport and proton gradient are used by ATP synthase to generate ATP through chemiosmotic coupling.

1. OXIDATIVE
PHOSPHORYLATION

2. INTRODUCTION
• Energy released during oxidation of glucose to CO2 is
retained in NADH and FADH2
• Electrons released from NADH and FADH2 and eventually
transferred to O2
• Large amount of energy released during oxidation is used in
the formation of ATP
NADH +
H+
NAD+
H20
½ O2
2e-
FADH2
FAD
H20
½ O2
2e-
-52.6 Kcal/mol -43.14 Kcal/mol

3. COMPLEX PROSTHETIC GROUP
COMPLEX I FMN, Fe-S
COMPLEX II FAD, Fe-S
COMPLEX III Heme, Fe-S
COMPLEX IV Heme, Cu+
•4 respiratory enzyme complexes-
Complex I - NADH Dehydrogenase
Complex II - Succinate Dehydrogenase
Complex III - Coenzyme Q-Cytochrome Reductase
Complex IV - Cytochrome c Oxidase
ELECTRON TRANSPORT CHAIN
•Electrons are transferred through a series of electron
carriers
•Present in inner mitochondrial membrane

4. COMPLEX I
• Large multi sub-unit
complex
• Passes electron from
NADH to coenzyme Q
• One FMN molecule and 6-
7 Fe-S center
• For each pair of electron
transport 4 protons are
pumped across inner
mitochondrial membrane
• Rotenone, Piericidin A –
inhibitors
4Fe-4S
Center
2Fe-2S Center

5. COMPLEX II
• Inner mitochondrial membrane
bound enzyme
• Conversion of Succinate to
Fumerate
• Electrons released are passes to
FAD and then to Fe-S center and
finally to coenzyme Q
COMPLEX II

6. COMPLEX III
• Complex I and II transfer
electron to it via CoQ
• Electrons are transferred
from CoQ to an Fe-S center
and subsequently to
cytochrome b and
cytochrome c1
• Each pair of electron is
responsible for pumping of 4
protons
• Mechanism involved in
proton pumping is called Q-
cycle
• Antimycin A - inhibitor
COMPLEX III

7. Q CYCLE
• Mechanism of participation for
ubiquinone
• Proposed by Peter Mitchell
• Ubiquinones are hydrophobic and
uncharged
Coenzyme-Q
•a benzoquinone linked to number of
isoprene molecule
•Ubiquinone, ubisemiquinone and quinol
•Not a protein bound prosthetic group
•Hydrogen carrier

8. COMPLEX IV
• Also called cytochrome c oxidase
• Catalyze the transfer of electron from the
reduced form of cytochrome c to molecular
oxygen
• 13 subunits and 2 heme group and three
copper ions
• Heme a and heme a3 Cua and Cub
• Cua to Cyt a to Cub to cyt a3 to O2
• Release of 2 electrons from two molecules of
reduced cytochrome c with 2 protons from
the matrix
• Total of 4 electrons are transferred for each O2
molecule reduced to form 2 water molecule
• Cyanide,azide and Carbon monoxide
COMPLEX IV

9. CHEMIOSMOTIC THEORY
•Peter Mitchell,1961
•Experimental proof by- Andre Jagendorf and Ernest Uribe,1966

10. ATP SYNTHASE
• Catalyzes ATP synthesis as protons
flow back through the inner
mitochondrial membrane
• Two components- F0 component
and F1 ATPase
• F0 – 1 ‘a’, 2 ‘b’, 9-12 ‘c’ subunits
• Oligomycin blocks flow of protons
• F1 - 3α, 3β, 1γ, 1δ, 1ε
• γ ε and c9-12 act as rotor
COMPLEX V

11. BINDING CHANGE MECHANISM
•Developed by
Paul Boyer
•ATP synthesis is
coupled with a
conformational
change in the ATP
synthase
•Proton
translocation
through F0
powers the
rotation of the γ
subunit
•Three states-
open, loose, tight
• O-L-T-O

12. THANK YOU