Fatty Acid Oxidation Flashcards
Biological roles of fat
- Hormones -> intracellular signalling
- Membrane lipids
- Storage fats
2+3 role in structure
Most common fat in food
Triacylglycerol -> more efficient storage than glycerol
Components in tracylglycerol
- Fatty acid
- Ester bond
- Glycerol
When does fatty acid oxidation occur?
Most important during fasting and starvation to make ketone bodies for the brain + sometimes during exercise
Sources of fat
- Some types of muscle fiber contain fat droplets
- Adipose tissue distributed around body -> main site of storage
- Liver can make fat + release into blood
- Fat circulates in the plasma
Fat circulates in the plasma as:
- Free fatty acids bound to albemin
2. TAG in ‘lipoproteins’
Lipoproteins
Outer layer = phospholipids with proteins attached to outside (antigens) and triacylglycerol on the inside
How do lipases release fatty acids?
- Hormone-sensitive lipase acts on TAG in intracellular lipid droplets stimulated by adrenaline, noradrenaline + low insulin.
- Lipoprotein lipase acts on TAG in lipoproteins. It’s secreted by tissues such as muscle + adipose
What is the difference between hormone-sensitive lipases and lipoprotein lipases?
- Hormone sensitive release fatty acid to be taken up by other cells.
- Lipoprotein store fatty acids in own cells
How do fatty acids enter the mitochondria?
- Sterified to FA coA by thioester bond
- ATP to AMP (alpha and beta phosphate bonds broken) enzyme can’t catalyze reverse reaction
- Able to enter mitochondria
Fatty acid oxidation doesn’t produce
ATP
Fatty acid oxidation produces
- NADH
- FADH2
- 2 Acetyl coA
Mechanism of FA oxidation
- FAacetylcoA -> Enoyl coA by FA coA dehydrogenase
- FAD -> FADH2 (oxidation)
- Hydroxy-acyl coA + H2O by hydroxy-acyl coA
- Keto-acyl coA by hydroxyl-acyl coA dehydrogenase
- NAD -> NADH
- Fatty acyl coA cleavage by thiolase + coASH
O2 is needed
to produce ATP from bi-products
Neurons don’t oxidise FA’s because
Low levels of thiolase
FA oxidation and glycolysis
don’t occur at the same time
FA oxidation doesn’t occur when
FA synthesis is ocuring in lvier
How can the biproducts of FA oxidation be used to make ketone bodies?
2 acetylcoA -> 2coASH -> Ketone bodies (4C)
Fats from digestion enters
lymph in lipoproteins
