Fatty Acid Degradation

Question 1

Stages of Fatty Acid Degradation

Answer 1

1. Release of fatty acids from TAG storage
2. Activation of fatty acids by linkage to acetyl-CoA
3. Fatty Acid oxidation generates acetyl-CoA, NADH, FADH2

Question 2

Release of fatty acids from TAG

Answer 2

• Fatty acids are stored in adipose tissue in molecules of TAG
• lipids must be mobilized from storage and transported to energy requiring tissues
• fats are released in response to hormones

Question 2

Fatty Acids and Glycerol Transported by Blood

Answer 2

• fatty acids are hydrophobic thus req. binding to albumin for transport
• glycerol is transported to liver (water soluble, used for substrate in gluconeogenesis)

Question 3

Hormone Sensitive Lipase

Answer 3

• glucagon/epinephrine stimulate fatty acid release in adipose tissue
• signalling cascade results in activation of lipases (hormone sensitive lipase and adipose triacylglyceride lipase)
• leads to production of glycerol and fatty acids

Question 3

Signal Cascades

Answer 3

• convert hormone or environmental stimuli into a cellular response
• activation of a receptor in cell membrane results in rxns to produce second messengers (cAMP, phosphorylation cascades)

Question 4

Preparation for oxidation

Answer 4

• fatty acids enter cell via transport proteins and shuttled about in association w/ fatty acid binding proteins
• oxidation occurs in mitochondrial matrix
• must transport fatty acids, first must activate (req. ATP)

Question 4

Transport into mitochondrial matrix

Answer 4

Activated fatty acyl-CoA can be transported across outer membrane of mitochondrion but not inner- require shuttle
- use carnitine shuttle to cross membrane then converted back to original carnitine

Question 5

Carnitine deficiencies

Answer 5

• Result in decreased ability to use long chain FAs for energy
• Accumulation of toxic amounts of FFA and acyl groups

Question 5

What is Carnitine Shuttle inhibited by?

Answer 5

inhibited by malonyl coA- intermediate of FA synthesis
- when FA synthesis occurs in cytosol, FAs are not transferred to the mitochondria
- mostly derived from diet, can be synthesized in liver from a.a

Question 6

Fatty acid oxidation

Answer 6

• FA is oxidized to acetyl-CoA removing 2 carbon atoms at a time as acetyl-CoA

Question 7

Four recurring rxns

Answer 7

• Ox. by FAD+
• Hydration
• Ox. by NAD+
• Thyolysis by coenzyme A

Question 8

Oxidation of Palmitate

Answer 8

• Number of cycles = 7 for palmitoyl CoA

Question 9

What does oxidation of palmitate produce?

Answer 9

• 7 FADH2
• 7 NADH
• 8 Acetyl-CoA

Question 10

What does final cycle of oxidation of palmitate do?

Answer 10

Final cycle takes acyl-CoA and removes 2 c’s as acetyl-CoA leaving an acetyl-CoA