definition of ETC, components f ETC, inhibitors of ETC

1. Electron transport chain (ETC)

2. Electron Transport chain
• Electrons carried by reduced coenzymes
(NADH or FADH2) are passed sequentially
through a chain of proteins and coenzymes (so
called electron transport chain)to O2 .
Electrons carried by reduced
coenzymes (NADH or FADH₂) are
passed through a chain of proteins and
coenzymes (so called electron
transport chain) to O₂ .

3. Electron transport chain
carbohydrate, Fatty acids, a.a
( metabolized)
NAD,FAD
mitochondria
NADH⁺, H⁺, FADH₂
(ETC)
transfer e-,liberate energy(ATP)
½ O₂

4. • outer membrane :-relatively permeable.
• inner membrane :- permeable only to those
things which have specific transporters .
- ETC & ATP synthesizing system located in it.
- Phosphorlyting subunits ( centers for ATP
production).
• Matrix :- enzymes for TCA, beta- oxidation &
oxidation of amino acid.
Mitochondria

6. Electron transport chain
• Final common pathway in the aerobic cells
by which electrons derived from various
substrates are transferred to oxygen .
• series of oxidation reduction enzymes,
coenzymes & electron carrier cytochrome.
• Location :- inner mitochondrial
membrane.

7. Components
• NAD ⁺
• NAD, FAD dehydrogenase
• FAD, FMN
• Coenzyme Q
• Iron containing proteins
- Iron sulfur protein associated with :-
- FMN & Cytochrome b
• Cytochrome b, c,c₁ & aa₃

8. Entry of electrons in respiratory chain

9. Nicotinamide nucelotide
• Found as two coenzymes :- NAD, NADP
• Derived from vitamin niacin .
• Involved in ETC .
• NAD⁺ is reduced to NADH + H ⁺ by dehydrognase
with removal 2 H atom.
• Substrate:- glyceraldehyde-3-P
- Pyruvate
- Isocitrate
- malate
-alpha keto-glutarate .

10. Flavoproteins
• NADH dehydrogenase is complex enzyme.
- Consist of non-heme iron , Fe S,
- Flavoprotein with FMN as prosthetic gp.
- FMN accept two e⁻& H⁺ to form FMNH ₂
• Succinate dehydrogenase also
flavoprotein with FAD as coenzyme

11. • Iron sulphur protein : - ( Fe S)
- Present in two form – oxidized & reduced
- One Fe S transfer e- from FMN to
coenzyme Q
- Other transfer e- from Cyt b to Cyt C.
• Coenzyme Q :- also called ubiquinone
- Lipid soluble.
- Transfer e- & protons from complex I ,II to
III.

12. Cytochromes
• Colored component
• Conjugated proteins, containing iron gp. as ferric
state.
• It accept e- & are reduced to ferrous .
• As the e- pass to next component it reoxidized to
ferrous
• Three types :- cyt a, cyt b, cyt c
- Cyt a :- a & aa₃
- Cyt c :- c & c₁
cyt b FeS cyt c cyt c ₁ cyt aa₃ O₂

13. Cytochrome c :-
- mw:- 13,000
- Small protein of 104 a.a. & heme gp.
- Central member of ETC.
- Loosely bound to inner mitochondrial
membrane.

14. • Cytochrome a & a3 :-
- Terminal component of ETC.
- React directly with molecular oxygen.
- Also contains copper.

15. Role of components
• NAD⁺ :- accept & transfers one H⁻(one H ⁺,2e⁻ )
• FMN or FAD or coenzyme Q:-
- accept & donates two hydrogen( H ₂ i.e. 2H ⁺ ,
2e-) at a time.
• Each cytochrome or iron sulfur protein :-
-accept & transfers one e- but no hydrogen ion.
How the electrons Transfer in ETC

19. COMPLEX V
ATP SYNTHASE
COMPLEX III
CoQ- Cytochrome
Reductase
COMPLEX IV
Cytochrome oxidase
COMPLEX I
NADH-CoQ-
Reductase

22. Complex II:
• Succinate dehydrogenase
(Succinate: CoQ oxidoreductase)
• Function:- transfer electrons from succinate to
CoQ
Components:-
Succinate dehydrogenase (FAD, Fe-S)
Cytochrome b

23. Complex III
• Co Q -Cyt c oxidoreductase
• Function: -transfer electrons from Co Q to
cytochrome c
• Components:- iron-sulfur protein
cytochrome b (b562, b566)
cytochrome c1

24. Complex IV
• Cytochrome oxidase
• Function: - transfer electrons from Cyt c to
molecule oxygen, the final electron acceptor.
• Components: - cytochrome aa₃
copper ion (Cu+)