fats

2. De Novo synthesis
of fatty acids
• Saturated fatty
acids are
synthesized from
acetyl CoA
derived from
glucose
• Occur in
cytoplasm
Elongation of fatty
acids
• Acetyl or malonyl
fragments are
added to the
existing fatty
acids
• Occur in both
microsomes and
mitochondria by
elongase enzyme
Desaturation of
fatty acids
• Double bonds are
introduced into
the fatty acids
• Occur in
microsomes

3. Acetyl CoA
Palmitic
acid
Stearic acid
Oleic acid
C-2
C-16 fatty acid
C-18 fatty acid
C-18 fatty acid, Unsaturated ∆9
De novo synthesis
Elongation
Desaturation

4. Definition
Differences
b/w synthesis
and oxidation
Phases of FA
synthesis
Reactions
[Pathway]
Regulation

5. Definition
De novo synthesis of fatty acid is
the synthesis of saturated fatty
acids from acetyl CoA that is
primarily derived from glucose

6. » Occurs mainly in and
LACTATING MAMMARY GLAND
synthesis means new synthesis from
amphibolic compounds
» In FA biosynthesis used as

7. » carbohydrate intake  - acetyl CoA  - fatty
acids synthesis
» Occurred in cytosol
» Need - acetyl CoA
- NADPH ( from HMP shunt )

10. SYNTHESIS DEGRADATION
Intermediates Linked to SH in Proteins
(Acyl Carrier Proteins)
Linked to CoASH
Site Cytosol Mitochondria
Enzymes Components of single
Peptide
Separate Polypeptides
Redox
Coenzymes
NADP+ / NADPH NAD+ / NADH

11. Transport of substrates into cytosol
Carboxylation of acetyl-CoA to malonyl-CoA
Utilization of substrate to form palmitate
By enzyme complex fatty acid synthase
Elongation and desaturation of palmitate
To generate different fatty acids

12. Phase I
Transport of substrates into cytosol
Carboxylation of acetyl-CoA to malonyl-CoA

13. Citrate Citrate
Oxaloacetate
Malate
Pyruvate
Pyruvate
Oxaloacetate

14. Phase I
Transport of substrates into cytosol
Carboxylation of acetyl-CoA to malonyl-CoA

16. Phase II
Utilization of substrate to form palmitate
By enzyme FATTY ACID SYNTHASE COMPLEX

17. » Is a
polypeptide
containing
seven enzyme
activities and
acyl carrier
protein (ACP)
segment

22. Condensation

23. Reduction

24. Dehydration

25. 5
Reduction

26. PALMITATE
THIOESTERASE
H2O

27. Acetyl CoA
Malonyl CoA
Acetyl S-enzyme
Acetyl malonyl S-enzyme
3-ketoacyl S-enzyme
3-Hydroxyacyl S-enzyme
2,3-Unsaturated acyl S-enzyme
Acyl S-enzyme
Fatty
acid
synthase
multienzyme
complex
Acetyl CoA
Acetyl transacylase
Malonyl transacylase
3-ketoacyl synthase
3-ketoacyl reductase
Dehydratase
Enoyl reductase
CoASH
Malonyl CoA
CoASH
CO2
NADPH+H+
NADPH
H2O
NADPH+H+
NADPH
Acetyl CoA
carboxylase
CO2
ATP
ADP + Pi
Biotin

28. Palmitoyl S-enzyme
Palmitic acid
Fatty
acid
synthase
multienzyme
complex
Thioesterase
Acyl S-enzyme 4 Carbon
16 Carbon
After cycling through steps
- seven times
2 5
H2O

32. Enzymes Metabolites
End
products
Hormones Diet
Fatty acid synthesis is regulated by

33. Enzymes • Acetyl CoA carboxylase
Metabolites • Citrate
End
products
• Palmitoyl CoA
Hormones
• Insulin
• Glucagon
Diet • High carbohydrate diet

34. Glucagon

35. High carbohydrate diet
Acetyl-CoA carboxylase
Insulin
High fat diet Starvation Diabetes mellitus
+ +
+
- -
-

36. Elongation of fatty
acids
• Acetyl fragments
(from malonyl
CoA) are added
to the existing
fatty acids
• Occur in both
ER and
mitochondria