Biochem 501: Lecture 26: Fatty Acid Synthesis

  1. Precursor for fatty acid synthesis:
    Acetate (Acetyl-CoA)
  2. Synthesis of fatty acids takes place through:
    Repetitive condensations
  3. Intracellular location of fat synthesis:
    • Animals: Mitochondria, Endoplasmic Reticulum, Cytosol
    • Plants:
    • Mitochondria, Chloroplasts, Peroxisomes
  4. Reactions in Mitochondria
    • Animal: Fatty acid oxidation, Acetyl-CoA production, ketone body synthesis, fatty acid elongation
    • Plant: No fatty acid oxidation
  5. Reactions in Endoplasmic reticulum
    • Phospholipid synthesis
    • Sterol synthesis (late stages)
    • Fatty acid elongation
    • Fatty acid desaturation
  6. Reactions in cytosol
    • NADPH production (pentose path, malic enzyme)
    • Isoprenoid/sterol synthesis (early stages)
    • Fatty acid synthesis
  7. Malonyl-CoA Synthesis
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    • Rate limiting/irreversible
    • Stimulated by citrate
    • Inhibited by Palmitoyl-CoA
    • Catalyzed by "biotin"
  8. Biotin Enzyme Structure
    3 sections, Biotin carboxylase, biotin carrier protein, and transcarboxylase
  9. Biotin Enzyme Function (Malonyl-CoA formation)
    Arm of biotin carrier protein binds CO2 with help of biotin carboxylase subunit, then moves to the transcarboxylase subunit to transfer CO2 to Acetyl-CoA
  10. Subunits of Fatty Acid Synthase Complex
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  11. Condensation of Acetyl and Malonyl (2nd step of fatty acid synthesis)
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  12. Reduction of Acetoacetyl-S-ACP (Third step of fatty acid synthesis)
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  13. Dehydration (Fourth step of fatty acid synthesis)
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  14. Second Reduction (Fifth step of fatty acid synthesis)
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  15. Overall Accomplishment of Fatty acid synthesis steps 1-5?
    Addition of two carbons to initial acetyl group.
  16. Acetyl-Carrying Protein (ACP)
    Carries Acetyl group along the Fatty Acid Synthesis complex to necessary enzymes.
  17. Net reaction for fatty acid synthesis
    N Acetyl-CoA + N-1 ATP +2(N-1)NADPH + 2(N-1) H+ -----> Fatty acid + ADP+Pi+NADP+ N-2 H2O
  18. What carries out elongation and desaturation of fatty acids
    Accessory enzyme systems
  19. FA Synthase Complex # of separate subunits
    • Animals=1 polypeptide
    • Yeast= 2 polypeptide
    • Bacteria/Plants= 7 polypeptides
  20. Sources of NADPH in Fatty Acid synthesis
    • Pentose Shunt
    • Breakdown of Malate in the adipose tissue into Pyruvate
    • Plant chloroplasts
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  21. Acetate Export from Mitochondria
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  22. Regulation of FA synthesis
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  23. Regulation of Fatty acid entrance into Mitochondria
    Fatty acids broken down inside mitochondria, made outside the mitochondria. When being created the second product, Malonyl-CoA, inhibits the protein responsible for taking FA in so that the loop isnt pointless
  24. Structures of Lipids
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  25. Biosynthesis of Triglycerides
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  26. Biosynthesis of Phospholipids
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Card Set
Biochem 501: Lecture 26: Fatty Acid Synthesis
Biochem 501