Electron transport chain,oxidative phosphorylation & mitochondrial

transport systems.

M.Kohutiar, B.Sopko

Content

1. Structure of mitochondriaMitochondrial transport systems

2. Electron transport3. Parts of Electron transport chain4. Proton gradient and synthesis of ATP5. Uncoupling

Metabolism ANABOLIC CATABOLIC

ΔG < 0 G < 0 ΔG < 0 G > 0

Gain of electron transport chain

O6H6CO6OOHC 2226126

molkJG /2823´0

Gain of electron transport chain

OHNADO2

1HNADH 22

n(ATP))P n(ADP i

Gain of electron transport chain

O6H6CO6OOHC 2226126

molkJG /2823´0

24e24H6CO6OOHC 226126

O12H24e24H6O 22

Gain of electron transport chain

COMPLEX I

COMPLEX II

COMPLEX III

COMPLEX IV

CoQ

cytochrome c

NADH

FADH2

-0,4

0,8

Gain of electron transport chain

COMPLEX I

COMPLEX II

COMPLEX III

COMPLEX IV

CoQ

cytochrome c

NADH

FADH2

-0,4

0,8

Gain of electron transport chain

COMPLEX I

COMPLEX II

COMPLEX III

COMPLEX IV

CoQ

cytochrome c

NADH

FADH2

-0,4

0,8 ΔE°´ > 0

Gain of electron transport chain

OHNADO2

1HNADH 22

n(ATP))P n(ADP i

COMPLEX I

COMPLEX II

COMPLEX III

COMPLEX IV

CoQ

cytochrome c

NADH

FADH 2

-0,4

0,8

GLYCOLYSIS

glucose

glucose-6-phosphate

glyceraldehyde-3-phosphate

1,3-bisphosphoglycerate

pyruvate

acetyl-CoA

NAD+

NADH

NAD+

NADH

isocitrate

2-oxoglutarate

sukcinyl-CoA

fumarate

malate

sukcinate

ocalacetate

citrate

NAD+

NAD+

NAD+

NADH

NADH

NADH

FADH2

FAD

CITRATE

CYCLE

acetyl-CoA

GLYCOLYSIS

glucose

glucose-6-phosphate

glyceraldehyde-3-phosphate

1,3-bisphosphoglycerate

pyruvate

acetyl-CoA

NAD+

NADH

NAD+

NADH

Mitochondrial anatomy

ATP – ADP translocase

Cofactors structure

Glycerolphosphate shuttle

CH2

CH

CH2

OH

OH

O P

CH2

C

CH2

O

OH

O P

cytosol mitochondria

glycerol-3-phosphate

dihydroxyacetone phosphate

NADH

NAD+

mitochondria

CH2

CH

CH2

OH

OH

O P

CH2

CH

CH2

OH

OH

O P

CH2

C

CH2

O

OH

O P

CH2

C

CH2

O

OH

O P

cytosol mitochondria

glycerol-3-phosphate glycerol-3-phosphate

dihydroxyaceton phosphatedihydroxyacetone phosphate

NADH

NAD+ FAD

FADH2

Glycerolphosphate shuttle

mitochondria

Malate-aspartate shuttle

CH

CH2

COOH

COOH

OH

cytosol mitochondria

malate

C

CH2

COOH

COOH

ONADH

NAD+

MDH

oxalacetate

mitochondria

CH

CH2

COOH

COOH

OH

cytosol mitochondria

malate

CH

CH2

COOH

COOH

OH

C

CH2

COOH

COOH

OC

CH2

COOH

COOH

ONADH

NAD+

NADH

NAD+

MDH MDH

malate

oxalacetate oxalacetate

Malate-aspartate shuttlemitochondria

CH

CH2

COOH

COOH

OH

cytosol mitochondria

malate

CH

CH2

COOH

COOH

OH

C

CH2

COOH

COOH

OC

CH2

COOH

COOH

O

COOH

C

(CH2)2

COOHO

NADH

NAD+

NADH

NAD+

MDH MDH

Glu

AspAST

malate

oxalacetate oxalacetate

ketoglutarate

Malate-aspartate shuttlemitochondria

CH

CH2

COOH

COOH

OH

cytosol mitochondria

malate

CH

CH2

COOH

COOH

OH

C

CH2

COOH

COOH

OC

CH2

COOH

COOH

O

COOH

C

(CH2)2

COOHOCOOH

C

(CH2)2

COOHO

NADH

NAD+

NADH

NAD+

MDH MDH

Glu

Asp

Glu

AspASTAST

malate

oxalacetate oxalacetate

a-ketoglutaratea-ketoglutarate

Malate-aspartate shuttlemitochondria

Electron transport

V32,0E NADH2eHNAD 0´

0,82VE OH2e2HO2

1 0´22

Electron transport

V32,0E NADH2eHNAD 0´

0,82VE OH2e2HO2

1 0´22

V 1,14(-0,32)-0,82E0´

kJ/mol 2201,14F2zFΔFFΔFG 0´0´

Electron transport

kJ/mol 30,5ΔFG ATPPADP 0´

Electron transport

kJ/mol 30,5ΔFG ATPPADP 0´

42%100218

30,53

Electron transport

kJ/mol 30,5ΔFG ATPPADP 0´

42%100218

30,53

V 0,162F-

30500

zF

ΔFGΔFE

0´0´

Electron transport

kJ/mol -69,5ΔFG

V 0,36ΔFE CoQ NADHCoQNAD0´

0´redox

Electron transport

kJ/mol -36,7ΔFG

V 0,19ΔFE cytCCoQcytCCoQ0´

0´redoxoxred

kJ/mol -69,5ΔFG

V 0,36ΔFE CoQ NADCoQNADH0´

0´

redox

Electron transport

kJ/mol -69,5ΔFG

V 0,36ΔFE CoQ NADCoQNADH0´

0´

redox

kJ/mol -36,7ΔFG

V 0,19ΔFE cytCCoQcytCCoQ0´

0´redoxoxred

kJ/mol -112ΔFG

V 0,58ΔFE OHcytCO2

1cytC

0´

0´2ox2red

Electron transport

kJ/mol -2,9ΔFG

V 0,015ΔFE CoQ FADCoQFADH0´

0´redox2

COMPLEX I

COMPLEX II

COMPLEX III

COMPLEX IV

CoQ

cytochrome c

NADH

FADH 2

-0,4

0,8

COMPLEX I

COMPLEX II

COMPLEX III

COMPLEX IV

CoQ

cytochrome c

NADH

FADH 2

-0,4

0,8

ADP

ATP

ADP

ADP

ATP

ATP

COMPLEX I

COMPLEX II

COMPLEX III

COMPLEX IV

CoQ

cytochrome c

NADH

FADH 2

-0,4

0,8

ADP

ATP

ADP

ADP

ATP

ATP

rotenone

antimycin A

cyanide

2 3

4 5

6

1[O2]

èasTime

2 3

4 5

6

1[O2]

Time

NAD+

2 3

4 5

6

1[O2]

èas

NAD+

rotenon

2 3

4 5

6

1[O2]

time

NAD+

rotenone

FADH 2

2 3

4 5

6

1[O2]

Time

NAD+

rotenone

FADH 2 antimycin A

2 3

4 5

6

1[O2]

Time

NAD+

rotenone

FADH 2 antimycin A

cyanide

Components of electron transport chainComplex I: NADH ubiquinonreductase

kJ/mol -69,5ΔFG

V 0,36ΔFE CoQ NADCoQNADH0´

0´

redox

FeS centres

Components of electron transport chainComplex II: succinate ubiquinon reductase

kJ/mol -2,9ΔFG

V 0,015ΔFE CoQ FADCoQFADH0´

0´redox2

Components of electron transport chainComplex III:ubiquinol-cytC-reductase

kJ/mol -36,7ΔFG

V 0,19ΔFE cytCCoQcytCCoQ0´

0´redoxoxred

Cytochromes

Components of electron transport chainComplex IV: cytochrome c oxidase

O2H)c(Fecyt 4O4H)c(Fecyt 4 23

22

Oxidative phosphorylationchemiosmotic theory (Mitchell)

• OXPHOS requires intact mitochondrial membrane

• Inner membrane is impermeable for some ions• Electron transport is accompanied by transport

of H+, and development of measurable gradient• Compounds which increase the membrane

permeability do not affect the electron chain but inhibit ATP synthesis

H+

H+

H+

H+

low H+

high H+

ADP ATP

++++ ++++ ++++ ++++ ++++ ++++

---- ---- ---- ---- ---- ----

Proton gradient

kJ/mol 21,5ΔFG zFΔF]pH[pHRTΔFG 0´exin

Proton gradient

kJ/mol 21,5ΔFG zFΔF]pH[pHRTΔFG 0´exin

Cytosolic side

Mechanism of redox loop

QH2

QH.

H+

e-

matrixinner membraneInterimemb.

space

Mechanism of redox loopmatrixinner membrane

Interimemb.space

QH2QH2

QH.

H+

e-

Mechanism of redox loopmatrixinner membrane

Interimemb.space

QH2QH2

QH.

QH.

H+

H+

e-

cyt bk

e-

Mechanism of redox loopmatrixinner membrane

Mezimemb.prostor

QH2QH2

Q

QH.

QH.

H+

H+

H+

cyt c

e-

e-

cyt bk

e-

Mechanism of redox loopmatrixinner membrane

Interimemb.space

QH2QH2

Q Q

QH.

QH.

H+

H+

H+

cyt c

e-

e-

cyt bk

e-

Mechanism of redox loopmatrixinner membrane

Interimemb.space

QH2QH2

Q Q

QH.

QH.

H+

H+

H+

cyt c

e-

e-

cyt bk

e-

e-

cyt bT

Mechanism of redox loopmatrixinner membrane

Interimemb.space

QH2QH2

Q Q

QH.

H+

H+

H+

cyt c

e-

e-

cyt bk

cyt bT

e-

e-

e-

H+

QH.

Structure of Complex V

3D Structure of Complex V

Schematic Structure of Complex V

Dam

Dam

Protonmotiv force and ATP synthesis

ATP synthesis

Regulation of oxidative phosphorylation

ATPccyt NAD2

1PADPccyt NADH

2

1 2i

3

Regulation of oxidative phosphorylation

ATPccyt NAD2

1PADPccyt NADH

2

1 2i

3

ADP

P.ADP

ccyt

ccyt

NADH

NADK i

3

22

1

Regulation of oxidative phosphorylation

ATPccyt NAD2

1PADPccyt NADH

2

1 2i

3

KATP

ADP.P

NAD

NADH

ccyt

ccyt i

2

1

3

2

i

3

22

1

P.ADPATP

ccyt ccyt

NADHNAD

K

Uncoupling

Aerobic vs. Anaerobic ATP production

Oxidation of 2 e- NADH ……. 2,5 mol ATP with consumption of 0,5 mol O2

1 mol of the substrate is oxidised via Complexes I, III, and IV

Oxidation of 2 e- FADH2 …… 1,5 mol ATP1 mol of the substrate is oxidised via Complexes II, III a IV

Total oxidation of 1 mol of glucose yields 30 – 32 mol ATP,