Fatty Acid Synthesis

Question 1

Name the two enzymes that can modify palmitate and what their roles are.

Answer 1

Elongase - extends the chain

Desaturase - add double bonds

Question 2

What is the overall reaction for the synthesis of pamitate?

Answer 2

8 AcCoA + 7ATP + 14NADPH + 14(H+) —> Palmitate + 8CoA + 7ADP + 7Pi + 14(NADP+) + 6water

Question 3

List the 4 molecules that can be produced from arachidonic acid and their effects.

Answer 3

Prostaglandins (red blood cell transit)
Thromboxanes (blood clotting)
Prostacyclins (vasodilators)
Leukotrienes (allergies/inflammation)

Question 4

What are the two enzymes that metabolize/modify arachidonic acid and one of the molecule types that each of the enzymes can form?

Answer 4

Cyclooxygenase (aka suicide enzyme): Prostaglandins, thromboxanes, prostacyclins

Lipoxygenase : Leukotrienes

Question 5

How does aspirin block prostaglandin synthesis? What is the solution?

Answer 5

Aspirin targets and inhibits cyclooxygenase, preventing prostaglandin synthesis and having an effect on gastric acid secretion.
Solution is Ibuprofen.

Question 6

What is the stopping point of FA synthesis?

Answer 6

Palmitate (C16)

Question 7

What is the reducing molecule in FA synthesis? What are the sources for this process?

Answer 7

NADPH

Sources include: PPP, malic enzyme, ICDH

Question 8

What is the shuttle that holds fatty acid synthase together?

Answer 8

ACP (acyl carrier protein)

Question 9

How many total cycles does it take to reach a 16 carbon palmitoyl group during FA synthesis?

Answer 9

1st round - 4 carbon, saturated fatty acyl-ACP
2nd round - 6
3rd round - 8

Total of 7 cycles

Question 10

How is palmitate released from palmitoyl-ACP?

Answer 10

Thioesterase cleaves ACP from the 16 carbon saturated palmitoyl group.

Question 11

What are the limitations to mammals face during desaturation (addition of double bonds) of FAs?

Answer 11

Mammals lack delta12 and delta15 desaturase, so mammals cannot synthesize linoleate or linolenic acid.