Electron transport chain (etc)

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 FADH ₂ ) are passed through a chain of proteins and coenzymes (so called electron transport chain) to O ₂ .

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

5. 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.

6. Components NAD ⁺ NAD, FAD dehydrogenase FAD, FMN Coenzyme Q Iron containing proteins Iron sulfur protein associated with :- FMN & Cytochrome b Cytochrome b, c,c ₁ & aa ₃

7. Entry of electrons in respiratory chain

8. 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 .

9. 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

10. 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.

11. 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 & aa ₃ Cyt c :- c & c₁ cyt b FeS cyt c cyt c ₁ cyt aa ₃ O₂

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

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

14. 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

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

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

17. 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

18. Complex IV Cytochrome oxidase • Function: - transfer electrons from Cyt c to molecule oxygen, the final electron acceptor. • Components: - cytochrome aa ₃ copper ion (Cu+)