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
