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16 Cards in this Set
- Front
- Back
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Fatty Acids |
Carboxylic acids with hydrocarbon chains 4-36 carbons Unsaturated = double bonds leads to kinks in structure Stored in adipocytes |
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Role of Fatty Acids |
Fuel - triacylglycerols(TAG) Phospho and glycolipids - signalling and structure Anchorage of proteins to membranes Hormones |
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Digestion of Fatty Acids |
Ingested in diet Bile salts emulsify fats in SI forming micelles Intestinal lipases degrade TAG FA are taken up by mucosa cells Converted back to TAG TAG and cholesterol into chylomicrons Chylomicrons move through lymph and blood to tissue Lipoprotein lipase activated by apoC-II in the capilliary degrades TAG to FA + Glycerol FA enters cells |
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Explain Regulation by Glucagon |
Glucagon binds to T7 receptor on cell Activated Adenylate cyclase Produces cAMP Activates PKA Phosphorylates Hormone Sensitive Lipases and Perilipin The lipases split TAG to FA FA move to the blood and are transported by albumin Moves from blood to target cell |
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What happens to Glycerol |
Via glycerol kinase Converted to Dihydroxyacetone phosphate Thus can enter glycolysis or gluconeogenesis |
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Methods of Lipolysis |
Adipose triglyceride lipase activated by perilipin - ATGL Hormone sensitive lipase - HSL Monoglyceride lipase- MGL |
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Fatty Acid Binding Protein Role |
Transporters Proteins Lipid droplets Membrane synthesis Signalling Enzyme activity Initiates transcription of NHR's Oxidation - Mitochondria - Peroxisome |
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Activation of FA |
Thioester linkage to CoA Outer mitochondrial membrane via Fatty Acyl CoA synthase Requires 1 ATP Produces 2Pi + Fatty acyl CoA
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Carnitine Shuttle |
Carnitine replaces CoA Transported into Mitochondria CoA replace Carnitine Enzyme in cytosol Carnitine acetyltransferase I Enzyme in Mitochondria Carnitine acetyltransferase II |
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FA Oxidation Step 1 |
Oxidation Reaction Via Acyl-CoA dehydrogenase Reduces FAD to FADH2 H lost from alpha C and beta C forming double bond |
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FA Oxidation Step 2 |
Hydration Reaction Via Enoyl-CoA hydratase Addition of H2O Previous double bond is removed, OH added to Beta C and H added to Alpha C to become CH2 |
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FA Oxidation Step 3 |
Oxidation Reaction Via Dehydrogenase NAD+ to NADH + H+ H on OH group removed to form Double O bond on beta C and H removed from beta C |
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FA Oxidation Step 4 |
Thiolysis Via Thiolase Requires CoA Splits the bond between alpha and beta C leaving a FACoA with 2 less C and produces Acetyl CoA This repeats until only Acetyl CoA is left |
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Oxidation of Unsaturated FA |
Cis double bonds are not recognised by Acyl CoA dehydrogenase An isomerase makes the double bond a trans bond For polyunsaturated FA the above happens but if another double bonds is adjacent a unsuitable intermediate is formed which is then reduced |
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Oxidation of odd chain FA |
Yield proprionyl CoA in final step Requires Vit B12 dependent enzyme - biotin enzyme Converted to succinyl CoA |
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Regulation of FA Oxidation |
Malonyl CoA- Inhibits Glucagon/Epinephrine - Increases PPAR-alpha Insulin- Inhibits Carnitine acyl transferase I preventing transport into mitochondria |
