Electron Transport Chain PKG. 2012

7/28/2019 Electron Transport Chain PKG. 2012

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Harliansyah, Ph.D

Human Blok Systems

Dental Medicine Program

YARSI UNIVERSITY @ 2012


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Mitochondria outer membrane relatively permeable

inner membrane permeable only to those things with

specific transporters Impermeable to NADH and FADH2 Permeable to pyruvate

Compartmentalization

Kreb's and -oxidation in matrix Glycolysis in cytosol


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Most energy from Redox electrons during metabolic reactions sent to NAD

and FAD Glycolysis

In cytosol

produces 2 NADH

Pyruvate dehydrogenase reaction In mitochondrial matrix

2 NADH / glucose Krebs

In mitochondrial matrix

6 NADH and 2 FADH2 / glucose


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Oxidative Level Phosphorylation


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Electron Transport Chain Groups of redox proteins

On inner mitochondrial membrane

Binding sites for NADH and FADH2 On matrix side of membrane

Electrons transferred to redox proteins

NADH reoxidized to NAD+

FADH2

reoxidized to FAD


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4 Complexes proteins in specific order

Transfers 2 electrons in specific order

Proteins localized in complexes Embedded in membrane

Ease of electron transfer

Electrons ultimately reduce oxygen to water

2 H+

+ 2 e-

+ O2 --

H2O


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Electron Transport Chain


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Complex 1 Has NADH binding site

NADH reductase activity

NADH - NAD+

NADH ---> FMN--->FeS---> ubiquinone

ubiquinone ---> ubiquinone H2 4 H+ pumped/NADH


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Complex II succinate ---FADubiquinone

Contains coenzyme Q

FADH2 binding site

FAD reductase activity

FADH2 -- FAD


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Complex III ubiquinone - ubiquinone ox

while cyt C gets reduced

Also contains cytochromes b proton pump 4H+

Adds to gradient

8 H+ / NADH

4 H+

/ FADH2


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Complex IV reduction of oxygen

cytochrome oxidase

cyt a+a3 red ---> oxidized state oxygen ---> water

2 H+ + 2 e- + O2 -- 2 H2O

transfers e- one at a time to oxygen

Pumps 2H+ out

Total of 10 H+ / NADH

Total of 6 H+ / FADH2


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Totals Proton gradient created as electrons transferred to

oxygen forming water

10 H+ / NADH

6 H+ / FADH2


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Generation of ATP Proton dependant ATP synthetase

Uses proton gradient to make ATP

Protons pumped through channel on enzyme From intermembrane space into matrix

~4 H+ / ATP

Called chemiosmotic theory


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ATP


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Sources of ATP


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TotalsNADH

10 H+ X 1 ATP = 2.5 ATP

4 H

+

FADH2

6 H+X 1 ATP = 1.5 ATP

4 H+


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Total ATP from mitochondrial matrix Pyruvate dehydrogenase

NADH .2.5 ATP

Krebs3 NADH X 2.5 ATP/NADH .7.5 ATP

FADH2 X 1.5 ATP / FADH2.1.5 ATP

GTP X 1 ATP / GTP ..1.0 ATP(from a separate reaction)

Total .12.5 ATP

(Per glucose = X 2 = 25 ATP)


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Review of ATP Production


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What about NADH from glycolysis? NADH made in cytosol

Cant get into matrix of mitochondrion

2 mechanisms In muscle and brain

Glycerol phosphate shuttle

In liver and heart

Malate / aspartate shuttle


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Glycerol Phosphate shuttle

http://courses.cm.utexas.edu/jrobertus/ch339k/overheads-3/ch19_glycerol-shuttle.jpg


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Glycerol phosphate shuttle In muscle and brain

Each NADH converted to FADH2 insidemitochondrion

FADH2 enters later in the electron transport chain

Produces 1.5 ATP


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Total ATP per glucose in muscle and brain Gycerol phosphate shuttle

2 NADH per glucose - 2 FADH2

2 FADH2

X 1.5 ATP / FADH2.3.0 ATP

2 ATP in glycoysis 2.0 ATP

From pyruvate and Krebs

12.5 ATP X 2 per glucose ..25.0 ATP

Total = 30.0 ATP/ glucose


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Malate Aspartate Shuttle

http://courses.cm.utexas.edu/emarcotte/ch339k/fall2005/Lecture-Ch19-2/Slide14.JPG


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in cytosol In liver and heart

NADH oxidized while reducing oxaloacetate to malate

Malate dehydrogenase Malate crosses membrane


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in matrix Malate reoxidized to oxaloacetate

Malate dehydrogenase

NAD+

reduced to NADH NADH via electron transport yields 2.5 ATP

Mlate Aspartate

Shuttle

in cytosol


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Total ATP per glucose in liver and heart Malate Aspartate Shuttle

2 NADH per glucose - 2 NADH

2 NADH X 2.5 ATP / NADH5.0 ATP

2 ATP from glycolysis..2.0 ATP

From pyruvate and Krebs

12.5 ATP X 2 per glucose ..25.0 ATP

Total = 32.0 ATP/ glucose


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Summary Total ATP / glucose

Muscle and brain 30.0 ATP Uses glycerol phosphate shuttle

Heart and liver 32.0 ATP Uses malate aspartate shuttle

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Electron Transport Chain PKG. 2012