Lipids 1/2

Question 1

What is the order of 4 reactions for making a fatty acid and the starting precursors vs for degrading the fatty acids

Answer 1

Making fatty acid: need Activated acyl group, activated malonyl group 
1. Condensation.
2. Reduction
3. Dehydration
4. Reduction
Breaking a fatty acid: need an activated acyl group
1. Oxidation
2. Hydration
3. Oxidation
4. Cleavage/ thiolysis

Question 2

Describe the 7 steps in the catalytic cycle by fatty acid synthase

Answer 2

1. ACP delivers the acetyl unit to Ketosynthase (KS). Malonyl acetyl transferase (MAT) then attaches a malonyl unit to ACP.
2. ACP then visits KS again and condenses the acetyl and malonyl units together to form beta-ketoacyl which is still attached to ACP
3. ACP delivers the beta ketoacyl to KetoReductase (KR) which reduces the keto group to an alcohol->b-hydroyl.
4. B-hydroxyl visits dehydratase (DH) to make enoyl (double bond) and take away water
5. The enoyl is delivered to Enoyl reductase (ER) where it is reduced
6. ACP hands the reduced product to KS and is recharged with malonyl CoA by MAT.
7. KS condenses the two molecules on ACP ready to begin another cycle

Question 3

What are the requirements of the synthesis of fatty acid palmitate

Answer 3

8 acetyl CoA + 7 (ATP + 2NADPH) + 6H+