Lecture 6 - Beta-oxidation Flashcards
What is beta-oxidation?
The sequential breakdown of fatty acids to yield acetyl CoA
Where does beta-oxidation occur?
Mitochondria
What happens to the acetyl CoA that is produced from beta-oxidation?
Enters TCA cycle and produces CO2 and energy
What is released during each round of beta-oxidation?
- Acetyl CoA (1 during normal rounds and 2 during the last round)
- NADH
- FADH2
What must happen to the fatty acid before beta-oxidation?
Must be activated by CoA-thiolester using 2 ATP
How is the reverse reaction of beta-oxidation prevented?
Pyrophosphatase pulls the reaction to completion by removing PPi
How are fatty acids transported to the mitochondria?
- Chains under or 12C bind to fatty acyl CoA synthetase that is bound to the mitochondrial outer membrane
- Chains over 12C use the carnitine shuttle
What are the steps of the carnitine shuttle?
1) Carnitine acytransferase 1 transfers the fatty acyl group from CoA to carnitine
2) Fatty acyl-carnitine crosses the inner mitochondrial membrane by facilitated diffusion via a transporter
3) Carnitine acyltransferase 2 in the matrix transfers the fatty acyl group back to CoA
How many carbons are removed during each round of beta-oxidation?
2
What is the function of acyl-CoA dehydrogenase?
Create a double bond between alpha and beta carbons
Which enzyme converts palmitoyl-CoA into trans-delta2-enoyl-CoA and what is the cofactor?
- Acyl-CoA dehydrogenase
- FAD -> FADH2
Which enzyme converts trans-delta2-enoyl-CoA into L-beta-hydroxyacyl-CoA and what is the coenzyme?
- Enoyl-CoA hydratase
- H2O in
Which enzyme converts L-beta-hydroxyacyl-CoA into beta-ketoacyl-CoA and what is the cofactor?
- Beta-hydroxyacyl-CoA dehydrogenase
- NAD+ -> NADH + H+
Which enzyme converts beta-ketoacyl-CoA into acyl-CoA and acetyl-CoA? What is the cofactor?
- Acyl-CoA acetyltransferase
- CoA-SH in
What is the function of acyl-CoA dehydrogenase?
Make a double bond between the alpha and beta carbons
