Chapter 17: Fatty Acid Catabolism

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Chapter 17 Fatty Acid Catabolism

• Dr. Clower
• CHEM 4203

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Catabolism of Fatty Acids

• Oxidation to form acetyl-CoA (b-oxidation)
• Large energy yield
• In this chapter
• Review of lipid properties
• Absorption, digestion, and transport of lipids
• Oxidation mechanisms (saturated, unsaturated,
  odd-chain)
• Ketone bodies

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Lipids

• Oils, fats, or fat-like material
• Some vitamins, hormones
• Not polymeric
• Aggregate
• Structural matrix of biological membranes
• Structural variety
• Largely hydrophobic
• Insoluble in water
• Soluble in organic solvents (chloroform, ether)
• Storage vs. structural

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Triacylglycerols

• aka triacylglycerides
• Fatty acid triesters of glycerol
• Simple or mixed
• Obtained from
• Diet
• Fat storage cells
• Endogenous

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Digestion and Absorption

• In small intestine
• Solubility factors
• Bile salts

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Processing of Dietary Lipids
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Triacylglycerol and Cholesterol Transport
Animated Figure
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Intestinal Fatty Acid Binding Protein

• Complexed with palmitate

PDB ID 2IFB
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Enzymatic Degradation of Triacylglycerols

• Step 2 lipase action

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Mechanism of Interfacial Activation
Nature 362, 793 (1993).
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Phospholipases
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Fate of Glycerol

• Glycerol formed from lipase action oxidized via
  glycolysis pathway

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Fatty Acid Oxidation

• b-oxidation
• Activation of fatty acids

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Transport into the Mitochondrion

• Acyl-carnitine/carnitine transporter

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Three Stages of Fatty Acid Oxidation

• b-oxidation
• Oxidation of acetyl-CoA
• Oxidative phosphorylation

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b-oxidation
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Step 1
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Step 2
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Step 3
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Step 4
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Oxidation of Palmitoyl-CoA

• Equation for one pass
• Overall equation
• Yield of ATP

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Oxidation of Unsaturated Fatty Acids
Linoleic acid
Oleic acid
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Oxidation of Oleic Acid
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Oxidation of Linoleic Acid
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Oxidation of Odd-Chain Fatty Acids
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Regulation of Fatty Acid Oxidation
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b-Oxidation in Peroxisomes
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Ketone Bodies
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Ketone Body Formation and Export
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End of Chapter 17