Fatty Acid Synthesis Flashcards
T or F: Fatty acid synthesis and oxidation are carried out by different pathways.
True
Where does fatty acid synthesis occur?
- Cytosole
Note: breakdown occurs in the mitochondria
What precursors are required for fatty acid synthesis?
- Pantothenic acid
- NADPH
- NADH
- ATP
Where is the enzyme that breaks down citrate located?
- What are its products?
- Citrate Lyase
- Located in the Cytosol
- Acetyl CoA and OAA
What is the fate of cytosolic Acetyl CoA?
- It will get made into a fatty acid
How many acetyle CoA molecules are required to make palmitate?
-How many of these acetyl CoA’s have to be 1st converted to malonyl CoA?
- 8 acetyl CoA’s needed
- 7 acetyl CoA’s of the 8 must first be converted to malonyl CoA
What effect does malonyl CoA have on fatty acid degration?
- Prevents Fatty Acids from entering the Mitochondria, which is the only place that degradation can take place
If CPT-1 was mutated and failed to respond to malonyl CoA, what would be the consequence?
- there would be Futile cycle of fatty acid synthesis and breakdown
T or F: after malonyl CoA is made, all reactions of fatty acid synthesis take place on a single enzyme complex
True, this is Fatty acid synthase
What type of bonds does Fatty acid synthase make with growing intermediates, and what does it use to make these bonds?
- Acyl Carrier protein part requires phospho-pantetheinyl prosthetic group (CoA)
- 2 sulfhydral groups are also used
What forms the initial thioester bond with malonylCoA?
Panthothenic Acid
Compare the 4 steps of Fatty acid oxidation to Fatty acid synthesis.
Oxidation:
- Oxidation
- Hydration
- Oxidation
- Cleavage
Synthesis:
- Condensation
- Reduction
- Dehydration
- Reduction
What are the 5 steps of Fatty acid synthesis?
- Transfer - malonyl to FA synthase
- Condensation - malonyl and an acyl group
- Reducion - ß-ketoacyl group with NADPH
- Dehydration - forms double bond
- Reduction - of double bond with NADPH
How many carbons are added with each cycle of the FA synthase complex?
2 with each round
What MUST be the acceptor of the malonyl transfer?
Acetyl CoA
How do VLDLs get broken down and absorbed?
- The same way that Chylomicrons do by LPL
T or F: acetyl CoA is the 2 carbon donor used in fatty acid synthesis
False, malonyl CoA is the 2 carbon donor
What differences are there between enzyme location and structure in fatty acid synthesis and degration?
- In synthesis a Multifunctional Complex is used in the CYTOSOL
- In degradation separated enzymes are used in the MITOCHONDRIA
What is the carrier in fatty acid oxidation and synthesis.
Synthesis - ACP
Oxidation - coenzyme A
What reducing agents are used in fatty acid oxidation and synthesis?
Synthesis - NADPH
Oxidation - NADH and FADH2
What are the primary agents for synthesis and oxidation of fatty acids.
Synthesis - Liver and Fat
Oxidation - Liver and Muscle
How are synthesis and oxidation affected by the insulin/glucagon ratio?
High insulin/glucagon = synthesis
Low insulin/glucagon = degradation
What step is regulated in fatty acid synthesis and what are the regulators?
- Fatty acyl CoA inhibits Acetyl CoA carboxylase
- Citrate upregulates Acetyl CoA Carboxylase
What inhibits ß-oxidation?
Malonyl CoA
