Biochem- Lipid Metabolism And De Nova Synthesis Flashcards
List the enzymes that convert Fatty acids into fatty acyl CoA.
- Synthetase or Thiokinase
- Acyl CoA
Where does the b-oxidation of fatty acids occur?
Cytosol, outside the mitochondria.
List the carrier substance that carried the acyl group into the mitochondrial membrane due to its impermeability.
Carnitine.
Describe the oxidation of fatty acids into Acetyl CoA.
- Once an active FA enters the mitochondria, acyl coA dehydrogenase removes the hydrogen to the a,b- bonds to α, β unsaturated fatty acyl CoA.
- Enoyl CoA hydratase adds a molecule of water to the α, β double bond to form β- hydroxyl acyl CoA.
- With the NAD present, β- hydroxyl CoA dehydrogenase oxidizes into β-ketoacyl CoA.
- Thiolase cleaves the β-ketoacyl CoA into Acetyl CoA and fatty acyl CoA.
- The fatty acyl CoA goes through process 1-4 6 more cycles to generate the remaining Acetyl CoA.
How many Acetyl CoA is generated from the b- oxidation of palmitic acid?
8.
Where are fatty acids activated and oxidized?
— fatty acids are activated in the cytosol.
— fatty acids are oxidized in mitochondria.
In the oxidation of odd chain fatty acids, what is left behind in place of the fatty acyl CoA and what is it converted to?
Propionyl CoA (3 carbon fragment) —> Succinyl CoA.
At the end of the oxidation of odd chain fatty acids, what is Succinyl CoA used in?
TCA cycle.
State the rate limiting step (Regulation) in the β- oxidation of fatty acids and what is it inhibited by.
Carnitine acyl transferase-1 (CAT -1).
Inhibited by: Malonyl CoA.
State the effect Malonyl CoA has on the β- oxidation of fatty acids.
- Malonyl CoA inhibits the CAT-1, therefore causing a decrease in fatty acids oxidation.
- A decrease in fatty acids oxidation leads to a decrease in the generation of Acetyl CoA.
During starvation, what happens to Malonyl CoA and CAT-1?
During starvation:
1) the decrease of insulin/ glycogen ratio.
2) Acetyl CoA dehydrogenase is inhibited (first intermediate of the biosynthesis of fatty acids to form Malonyl CoA) and decreases the production of Malonyl CoA.
3) With a decrease in Malonyl CoA, it releases the inhibition of CAT-1 and increase Acetyl CoA production for oxidation.
List the organelle that conduct the oxidation of long chain fatty acids.
Peroxisomes.
What is the long fatty acid chain reduced to in Peroxisomal fatty acid oxidation?
Octanoyl- CoA.
State what happens to Octanoyl-CoA after it is reduced.
After it is reduced, it leaves the Peroxisomes and enters the mitochondria via carnitine where it goes through B-oxidation.
Describe the Zellweger syndrome.
A inherited, rare, inborn error of peroxisomal oxidation of fatty acid oxidation that is caused by a lack of functional Peroxisomes.
Note: Due to the low oxidation, the long chain fatty acids accumulate in the brain, kidney and muscle.
