Metabolism of Adipose TAGs and Ketone Bodies

Question 1

Function of hormone-sensitive lipase

Answer 1

use water to cleave 3 fatty acids off of TAG

Question 2

How are fatty acids transported through the blood?

Answer 2

albumin boats - carry up to 10 each

they’re hydrophobic

Question 3

How are fatty acids released from the perilipin?

Answer 3

Glucagon and epinephrine activate kinase A
Kinase A phosphorylates perilipin and hormone-sensitive lipase (HSL)
HSL cleaves TAGs as they come thru the protein layer

Question 4

What is peroxisomal B-oxidation?

Answer 4

oxidation of very long chain un/saturated FAs (>22C), very long branched FAs, and very complex cyclic and hydroxyl groups

Question 5

Defects in peroxisomal B-oxidation

Answer 5

infant seizures and progressive neruorological dysfunction

Question 6

Order of enzymes for Peroxisomal B-oxidation

Answer 6

ACOX (Acyl-CoA Oxidases)
D-bifunctional protein (DBP)
Thiolase

Question 7

What changes in UNsaturated FA B-oxidation?

Answer 7

For every C=C –> you skip the 1st step and lose out on FADH2 (lose 1.5 ATPs)

Question 8

How can you perform B-oxidation on odd-chained FAs?

Answer 8

Proceed as normal until 3Cs left
Proponoyl-CoA —(Proponoyl-CoA carboxylase + biotin) –>D-methylmalonyl-CoA —(epimerase)–> L-methylmalonyl-CoA
–Adds a carbon to the chain and adds it into the succinyl CoA part of the Krebs Cycle

Question 9

What is omega-oxidation?

Answer 9

Add a carbonyl group to the omega end of the FA chain and can chomp away at both ends
End product is succinyl diCoA and gets converted to succinyl CoA of the Krebs Cycle

Question 10

What are the 2 roles of the liver during the fasted state?

Answer 10

make glucose for everyone

breakdown fat for everyone (cleaves FAs from adipose and makes ketone bodies)

Question 11

What is a ketone body?

Answer 11

4Cs made from 2 acteyl CoAs

Question 12

Ketoacidosis

Answer 12

abundance of B-hydroxybutarate – lowers pH

Question 13

What ketone body gets circulated around the blood?

Answer 13

B-hydroxybutarate –> made from acetoactetate & B-hydroxybutarate dehydrogenase
(NADH+H+ –> NAD+)

Question 14

Why does succinyl-CoA:3-oxoacid-CoA transferase 1 appear everywhere but the liver?

Answer 14

Don’t want to breakdown ketone bodies right after making them

Question 15

Where does the brain get its “carb flame” from? (glucose)

Answer 15

1) gluconeogenic glucose
2) lactate from muscle
3) glycerol from adipose lipolysis of TAGs

Question 16

What happens if there is a deficiency in ACOX (peroxisomal B-oxidation)?

Answer 16

infant seizures and neurological disfunction