Chapter 17: fatty acid catabolism

What are the organs that use the oxidation of fatty acids for major source of energy

heart and liver

define ß-oxidation

oxidation of fatty acyl group at the C3 or ß position (after carbonyl group group at C1 activation of CoA)

How many carbon atoms are in palmitoyl- CoA and how many cycles of beta oxidation does it undergo

16

7

What are the products of beta oxidation

NADH, FADH2, acetyl-CoA

What is the formula that fatty acids are stored in the human body

R-CH2-CH2-COO-

what is the atp yield of complete beta oxidation of palmitoyl-CoA

106 (108-2)

what are the two main locations in the body where adipose tissue is located

subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT)

What are the three stages of triacylglycerol by which they are made accessible

degradation of TAG to release one fatty acid and glycerol in the blood for transport

activation of fatty acids and transport to mitochondrial matrix for oxidation

degradation of fatty acids to acetyl-CoA by the Krebs cycle

list steps 1-8 of fats being absorbed into the small intestine

1. bile salts emulsify dietary fats in SI making micelles

2. Intestinal lipases degrade triacylglycerols

3. fatty acids taken up by mucosa and converted into triacylglycerols

4. Triacylglycerols are incorporated with cholesterol and apolipoproteins into chylomicrons

5. chylomicrons move through the lymphatic system and bloodstream to tissues

6. lipoprotein lipase activated in capillary converts triacylglycerols to fatty acids and monoacylglycerols

7. fatty acids enter cell

8. fatty acids are oxidized ad fuel or re esterified for storage

describe lipolysis

triacylglycerol use lipase to convert to glycerol and fatty acids

lipid breakdown

what is the role of cAMP in regulation of lipase in adipose cells

activates protein kinase A, which starts the process of getting glycerol to the blood stream and fatty acids into mitochondria

what is the importance of chylomicrons

They are transport vesicles for fats formed in the intestines

what is the function of serum albumin in the transport of fatty acids

a blood protein that binds and transports FFAs to their target tissues (almost ½ of total serum protein)

What is the reaction of the conversion of glycerol to glycerol-3-phosphate and dihydroxyacetone phosphate

glycerol —[(glycerol kinase) ADP→ATP] → glycerol 3-phosphate —[(glycerol 3-phosphate dehydrogenase)NAD+→NADH +H+]→ dihydroxyacetone phosphate

what is the biological importance of glycerol converting into glycerol to glycerol-3-phosphate and dihydroxyacetone phosphate

they further convert into glyceraldehyde 3-phosphate to enter glycolysis and biologically available energy is stored in three long-chain fatty acids

fatty acyl-CoA synthetase

activate fatty acid by conversion to fatty acyl-CoA thioesters

located in the mitochondrial membrane

what is the reaction that links CoA to fatty acids

fatty acid + CoA +ATP→ ← fattyacyl-CoA +AMP+ PPi

what is the importance of pyrophosphate

helps to make sure the reaction does not reverse and is used to convert ATP→AMP

further hydrolyzed to 2 Pi

role of aceyl-adenylate

acts as an electrophile, allowing the thioester fatty acyl-CoA to form and release AMP

What is carinitine’s role in moving fatty acids from the cytoplasm to mitochondria

Transported fatty acyl-CoA destined for mitochondrial oxidation across the inner mitochondrial membrane

what is CAT 1

carnitine acyl-transferase 1: catalyzes transesterification to transiently attach fattyacyl-CoA to the hydroxyl group of carnitine to form acyl-carnitine

what is CAT2

carnitine acyltransferase 2: transfers fatty acyl group from carnitine back to Coenzyme A to regenerate fatty acyl-COA and free carnitine

acylcarnitine (carnitine cotransporter)

uses passive transport of fatty acyl carnitine ester moves one carnitine into intermembrane space as one fatty acyl carnitine moves into matrix

what is the rate-limiting step for oxidation of fatty acids in mitochondria

carnitine-mediated entry

what is CAT1 inhibited by

malonyl-CoA the first intermediate in fatty acid synthesis

what are the four steps for fatty acid degradation

1. Oxidation of beta carbon (catalyzed by acyl-CoA dehydrogenase) generates trans-∆2-enol-CoA and FADH2

2. Hydration of trans-∆2-enoyl CoA by enoyl CoA dehydrogenase → L-3-hydroxyacyl CoA

3. Oxidation of l-3-hydroxyacyl CoA by L-3-hyrodoxyacyl dehydrogenase generating 2-ketoacyl CoA and NADH

4. cleavage of 3-ketoacyl CoA by thiolase forms acetyl CoA and fatty acid chain two C shorter

What is the importance of NAD+ and FAD in beta oxidation pathway

FAD converted to FADH2 as cofactor for acylCoA dehydrogenase to donate e-‘s to respiratory chain

NAD converted to NADH as cofactor for ß- hydroxyacyl-CoA dehydrogenase

What are Keaton bodies and where are they produced

A tone, acetoacetone, and ß-hydroxybutyrate formed from acetyl-CoA in liver

What happens during starvation and how does the body get its energy needs

After 3 days 1/3 of energy comes from ketone bodies, by over production of acetyl-CoA. Because of this ketosis occurs

What is the effect of high levels of acetoacetate

Acidosis, lowering blood pH

What can happen due to excess production of ketone bodies (ketosis)

Ketoacidosis where the blood becomes acidic (type 1 diabetes)