Glucose CatabolismRespiratory Chain

• Respiration: a process changes reducing power into a biological useful energy form ATP.

– Aerobic respiration: oxygen is the final electron acceptor, the product is H2O.

– Anaerobic respiration: the final electron acceptors are other than oxygen such as NO3

-, SO42-, Cu2+, and Fe3+.

• Respiratory chain is the electron transport chain for formation of ATP by transferring electrons from the carriers such as NADH to an electron acceptor.

Glucose CatabolismRespiratory Chain-Oxidative Phosphorylation

“Oxidative Phosphorylation is the electron transport chain that forms ATP as electrons are transferred from NADH or FADH2 to oxygen by a series of electron carriers” (L. Stryer, 1988)

- electron acceptor: oxygen (aerobic condition)- generate ATP, H2O- from NADH or FADH2

Taking place in mitochondria in eucaryotesor in cytoplasmic membrane in procaryotes

http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/oxidative/oxidativephosphorylation.html

Glucose CatabolismOxidative Phosphorylation

• In the process of Oxidative Phosphorylation

In eucaryotes:

NADH + H+ 3 ATP

FADH2 2 ATP

In procaryotes:

NADH + H+ ≤2 ATP

FADH2 ATP

Glucose Aerobic CatabolismReaction Summary

• EMP (glycolysis)Glucose + 2ADP + 2 NAD+ + 2 Pi →2 pyruvate + 2 ATP+ 2 (NADH + H+)

• Entry of pyruvate2pyruvate + 2NAD+ + 2CoA-SH →2 acetyl-CoA + 2CO2 + 2(NADH + H+)

• TCA cycle2acetyl-CoA + 6 NAD + 2FAD + 2GDP+ 2Pi + 4H2O → 2CoA + 6(NADH

+ H+) +2FADH2+2GTP (~ATP) + 4CO2

• Oxidative Phosphorylation In eucaryotes

EMP: 2 NADH → 2 FADH2 → 4 ATP (glycerol phosphate shuttle)Entry of pyruvate and TCA: 8 NADH → 24 ATPTCA: 2FADH2 → 4 ATP

The overall reaction:Glucose + 6O2 + 36ADP + 36 Pi → 6 CO2 + 6 H2O + 36 ATP

http://www.metabolic-database.com/html/body_lipogenesis__prevention_of_fat1.html

Glucose Catabolism

Glucose

Aerobic metabolism Anaerobic metabolism

Tricarboxylic acid (TCA)or (Krebs)or (Citric acid cycle)

Respiratory chain:Oxidative phosphorylation

Glycolysis orEmbden-Meyerhof-Parnas (EMP)

Fermentation: ethanol, acetic acid, lactate.

Glucose Anaerobic CatabolismGlycolysis (EMP)

Ethanol Production

Glycolysis (EMP)

Fermentation

Pyruvate

Decarboxylase

Alcohol dehydrogenase

Hydrocarbon Catabolism• Hydrocarbon: C & H

- Aliaphatic hydrocarbon

e.g. octane, C8H18

polyethylene –HC=CH-- Aromatic hydrocarbon

naphthalene

• Metabolism of hydrocarbon- Requires oxygen- Hydrocarbons are converted to acetyl-CoA which is metabolized by TCA cycle.- Challenges : low solubility in aqueous solution.

available microorganisms are limitedPseudomonas, Mycobacteria

naphthalene

http://umbbd.ahc.umn.edu/naph/naph_image_map.html

http://umbbd.ahc.umn.edu/naph/naph_map.html

http://www.dcs.napier.ac.uk/~cs203/catech.html

Naphthalene Pathway

Nitrogen Compounds CatabolismNitrogen compounds can be used for C, N and energy

sources

Proteins → peptides → amino acids → converted other amino acids or organic acids and ammonia by deamination.

- organic acids: acetyl-CoA into TCA cycle, lipids- amino acids: proteins, other amino acids or enter

TCA cycle- ammonium: amino acid, protein, nucleic acids

Nucleic acids → ribose/deoxyribose, phosphoric acid and purine/pyrimidine

- sugar: glycolysis and TCA- Phosphoric acid: ATP, lipids, nucleic acids- bases: nucleic acids, urea, acetic acids

Photosynthesis

Glycolysis and TCA

Overview of Biosynthesis• Pentose-phosphate pathway (hexo-

monophosphate pathway (HMP):

convert glucose-6-phosphate into carbon skeletons of C3 ~ C7 .

• Polysaccharides: glycan, glycogen

gluconeogenesis

• Lipids

• Proteins

• Nucleic acids (DNAs, RNAs)

1

4

5

2

6

3

Summary of Metabolism Pathways• Metabolism:

- catabolism: ATP, C skeleton for further biosynthesis- anabolism: biosynthesis requiring energy

• Bioenergetics: - energy storage and carrier ATP - Reducing power carriers: NADH, NADPH, FADH2

• Glucose catabolism:

Summary of Metabolism Pathways• Glucose catabolism:

Glucose

Anaerobic metabolism

Tricarboxylic acid (TCA)or (Krebs)or (Citric acid cycle)

Respiratory chain:Oxidative phosphorylation

Glycolysis orEmbden-Meyerhof-Parnas (EMP)

Fermentation: ethanol, acetic acid, lactate.

Aerobic metabolism

Summary of Metabolism Pathways

- Under aerobic condition, one molecule of Glucose catabolism generates:

in Glycolysis, 2 ATP, 2 NADH and 2 pyruvate

in TCA cycle, 6 (NADH+H+), 2FADH2, 2GTP, and 4CO2

in oxidative phosphorylation:

NADH, FADH2, O2→ ATP, H2O

Summary of Metabolism Pathways

- Under anaerobic condition, Glucose catabolism includes Glycolysis and fermentation:

Products: ethanol, lactic acid, ATP, etc.

• Nitrogen compound catabolism

• Hydrocarbon catabolism

• Photosynthesis

• Biosynthesis