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D- Beta Oxidation

D- Beta Oxidation. The break down of a fatty acid to acetyl-CoA units…the ‘glycolysis’ of fatty acids. STRICTLY AEROBIC. Occurs in the mitochondria. Acetyl-CoA is fed directly into the Krebs cycle. Overproduction causes KETOSIS. Exemplifies Aerobic Metabolism at its most powerful phase.

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D- Beta Oxidation

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  1. D-Beta Oxidation The break down of a fatty acid to acetyl-CoA units…the ‘glycolysis’ of fatty acids STRICTLY AEROBIC Occurs in the mitochondria Acetyl-CoA is fed directly into the Krebs cycle Overproduction causes KETOSIS Exemplifies Aerobic Metabolism at its most powerful phase

  2. Fatty Acid Oxidation Schedule of Topics • Digestion, absorption and transport • General mechanism of fatty acid oxidation • Oxidation of unsaturated fatty acids • Odd chain fatty acids…role of vitamin B12 • Ketone bodies and ketosis

  3. HS-CoA ATP PPi AMP CH3CH2CH2COOH [CH3CH2CH2CO-AMP] Fatty acyl CoA Ligase CH3CH2CH2CO~SCoA Fatty acyl CoA Prepares a Fatty Acid for transport and metabolism

  4. HS-CoA HS-CoA + Carnitine Acyl transferase I Acyl transferase II N(CH3)3 FA~CoA CH2 H-C-OH CH2 COO- Carnitine Transport into Mitochondria depends on Carnitine FA~CoA FA~Carnitine Translocase FA~Carnitine Carnitine

  5. CH3CH2CH2CH2CH2CH2CH2C~SCoA CH3C~SCoA CH3C~SCoA CH3C~SCoA CH3C~SCoA O O O O O Beta Oxidation 8 carbon Fatty Acid Acyl-CoA 4 two carbon Acetyl-CoAs

  6. Knoop’s Experiment Phenylacetate Benzoate

  7. B E T A O X I D A T I O N b a a b C H C H C H C O O C H C H C O O 2 2 2 2 2 H H b a C H C C C O O 2 H H H b a C H C C C O O 2 H H H b a C H C C C O O 2 H O H H b a C H C C C O O 2 H O

  8. β R -C…...CH3-C~S-CoA CH3CH2CH2CH2CH2CH2CH2C~S-CoA Cofactor or Substrate -C- CH2-C~S-CoA H O H O O O O O -C- CH2-C~S-CoA -C=C-C~S-CoA S-CoA O H H O MECHANISM Round Dehydrogenase FAD TRANS Hydratase H2O L- Dehydrogenase NAD+ Acyl Transferase HS-CoA

  9. Remember Trans L Vania When you think of beta oxidation

  10. THE ENERGY STORY PART I Glucose C6H12O6 + 6O2 → 6CO2 + 6H2O ΔHo = -2,813 kJ/mol = - 672 Cal/mol = 3.74 Cal/gram Stearic Acid C18H36O2 + 26O2→ 18CO2 + 18 H2O ΔHo = -11,441 kJ/mol = - 2,737 Cal/mol = 9.64 Cal/gram On a per mole basis a typical fatty acid is 4 times more energy rich that a typical hexose

  11. Energy Story Part II 1.0 g glucose = 3.7 kcal (15.5 kJ) 1.0 g stearic acid = 9.7 kcal (40.5 kJ) ENERGY CONSERVATION Stearic Acid (C18 satd) Textbook 9 Acetyl CoA = 108 ATP (90) 8 FADH2 = 16 ATP (24) 8 NADH = 24 ATP (20) = 148 ATP (134) - 1 ATP -1 147 ATP (133)

  12. Palmitoyl-CoA (Textbook) Palmitoyl-CoA + 7CoA + 7FAD + 7NAD+ + 7H2O 8 Acetyl-CoA 80 ATP 7 FADH2 10.5 ATP 7 NADH + 7H+ 17.5 ATP 108 ATP

  13. R-3 R-2 R-1 CH3CH2 CH2CH2 CH2CH2 CH2CO~SCoA FAD FAD FAD NAD+ NAD+ NAD+ HS-CoA HS-CoA HS-CoA C-8 Octoyl-CoA + 3HSCoA + 3FAD + 3NAD+ + 7H2O 4 Acetyl-CoA 40 ATP 3 FADH2 4.5 ATP 3 NADH + 3 H+ 7.5 ATP 52 ATP

  14. β2 β1 β3 CH3CH2 CH2CH2 CH2CH2 CH2CO~SCoA FAD NAD HSCoA CH3CH2 CH2CH2 CH2CO~SCoA FAD NAD HSCoA CH3CH2 CH2CO~SCoA FAD NAD HSCoA CH3CO~SCoA CH3CO~SCoA

  15. Hexanoic acid (C6H12O2) Glucose (C6H12O6) Hexanoic acid Glucose Hexanoyl-CoA -1 ATP 2 pyruvates 2 ATP 2 NADH + H+ 5 ATP Hexanoyl-CoA 2 pyruvates 3 Acetyl-CoA 30 ATP 2 Acetyl-CoA 20 ATP 3 ATP 2 FADH2 2 NADH + H+ 5 ATP 2 NADH + H+ 5 ATP 32 ATP 37 ATP Mwt = 116 Mwt = 180 ATP per Gram = 0.32 ATP per Gram = 0.17

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