Lipid Oxidation Flashcards
what does gall bladder do
emulsify fat into little lipid drolplets to make them more accesible to lipases which break them down into individual FA’s and reincorporated into triglycerides and put into a chilomicron
Where do chilomicrons tracel
blood vessels and lymph to deliver FA’s through lipo protein lipase which is activiated by insulin which helps break down FA’s and allow them to be absorbed. Glycerol goes back into bloodstream to be reabsorbed. through
What is B-48
protein component of chylomicron recognized by lipoprotein lipase.
What are the major classes of human plasma lipoproteins
- chylomicrons
- VLDL
- LDL
- HDL
Which two lipoproteins have the highest amount of triacylglycerols
- Chylomicrons; dietary lipid
2. VLDL; lipid from liver
What is ApoB-100
What LDL receptors bind to and bring it in; if you have a mutation in LDL receptor you get problems with cardiovascular system
What is LCAT
enzyme that HDL uses this when it scavengers cholesterol from bloodstream.
What activates LCAT
Apo A
What are the apolipoproteins
- Apo A
- Apo B-100: Ligand for receptor
- Apo B-48: structural role
- Apo C-II; Activator of lipoprotein lipase
- Apo E: ligand for receptor
What are the principal enzymes in lipoprotein metabolism
- LCAT
- Lipoprotein lipase (LPL
- Hepatic lipase
- acid lipase
- MTP
What activates uptake of fat from chylomicrons
lipoprotein lipase
What are healthy levels LDL and HDL
LDL: 40 mg/dL mdn
>50 mg/dL women
WHat are healthy cholesterol levels
<200
What is healthy level of triglycerides
<100-150
Where are lipoprotein lipases found
found on endothelial cell surface, mostly around adipose, heart and skeletal muscle
what activates lipoprotein lipase
insulin
Glycerol remains in bloodstream and is ____to liver for _____
recycled; gluconeogenesis
What hormone is released when we’re fasting to release free fatty acids and glycerol
Hormone sensitive lipase
what are perilipins
keep lipid droplet in adipocyte in tact and prevent release of triglyceride prematurely.
What does hormone sensitive lipase do
cleave off individual FA from triglyceride and release it into the bloodstream
What are two targets of protein kinase A
perilipins and hormone sensitve lipase
Describe fatty acid activation
- convert FA to acyl coA derivatives using Acyl CoA synthetase
Conversion of FA to an activated acyl derivative requires ____high energy phosphate bonds
2
FA must be activated to ____in order to be transported into the mitochondria to initiate ____
FACoA; beta oxidation
What is carnitine
Derived from lysine; carrier for lipids; transports fatty acyl-CoA into mitochondria for oxidation
What happens when you have carnitine deficiency? What if you have too much of it?
hypoketotic hypoglycemia-cant oxidize fat so losing out on production of energy;
too much results in conversion to TMAO by gut flora which promotes atherosclerosis
What does carnitine acyltransferase 1 do
Swap CoA carrier to carnitine carrier–> fatty acyl carnitine transfers fatty acyl carnitine in and free carnitine back out.
What does carnitine acyltransferase II do
Converts FA from carnitine back to fatty acyl CoA
What does malonylCoA inhibit
CAT 1 which prevents futile cycle of FA breakdown and synthesis happening simultaneously
What is the first stage of fatty acid oxidation
- Beta oxidation: NADH and FADH2 made go to electron transport chain. Acetyl CoA go to TCA cycle
What happens during beta oxidation
- Dehydrogenation: Make a keto group on beta carbon by converting single bond to DB by degydrogenation. H’s then get donated to FAD to make FADH2 to go into electron transport chain.
- Hydrate DB to make hydroxyl group by using NAD to make NADH to go to ETC
- Cleave by thialase to reduce the length of chain to make new fatty acyl CoA and released an acetyl CoA which goes to TCA cycle
How many cycles does it take for beta oxidation
7
what is the yield for palmitate
8 Acetyl CoA
7 NADH
7 FADH2
How many ATPs can you make from oxidation of fat
129
What is the deficiency in medium chain Acyl CoA dehydrogenase
Most common defect in fat metabolism; genetic disorder in infants causes fasting hypoglycemia. Dont have energy from fat being produced.
Most FA contain ___DB, but in oxidation we produce____DB. Unsaturated fatty acids cause decrease in ATP produced because you have to use energy to move DB around to change its configuration.
cis; trans
Oxidation of odd-chain FA can produce what?
Only release acetyl CoA and 3 carbon compound -1 Propionyl CoA which can be converted to succinyl CoA which goes into TCA cycle to form oxaloacetate. This can form glucose!
Rate limiting step of FA oxidation
Transport of fats into mitochondria
What are the steps of FA synthesis
- High blood glucose activates insulin
- Phosphatase removes phosphate groups on acetyl CoA carboxylase and activates it.
- Low blood glucose activates glucagon which activates protein kinase A which phosphorolates acetyl CoA carboxylase and inactivate it.
What can block CAT 1
malonyl CoA; so we cant hook FA to carnitine carrier to get it into mitochondria
Fatty acid oxidation occurs in all tissues except ___ and ____
brain and erythrocytes
Where does FA oxidation occur
mitochondrial matrix
What does FA oxidation require
acetyl CoA, FAD, and NAD+
What is FA oxidation inhibited by
malonyl CoA
When does FA occur
low energy state (high ADP) and during fasting. (high glucagon)
Where does FA synthesis occur
in liver and adipose in cytosol
What is required for FA synthesis
Acetyl CoA, NADPH, malonyl CoA
What activates FA synthesis
citrate
What is FA synthesis inhibited by
long chain acyl CoA
When does FA synthesis occur
high energy state. Lots of ATP present; Usually after carbohydrate feeding. (high insulin)
