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FATTY ACID OXIDATION

FATTY ACID OXIDATION. OBJECTIVES. FATTY ACID OXIDATION Explain fatty acid oxidation Illustrate regulation of fatty acid oxidation with reference to its clinical disorders. GLUCOSE HOMEOSTASIS DURING FASTING. Triacylglycerol. Fatty acids. Glycerol. FATTY ACID OXIDATION.

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FATTY ACID OXIDATION

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  1. FATTY ACID OXIDATION

  2. OBJECTIVES • FATTY ACID OXIDATION • Explain fatty acid oxidation • Illustrate regulation of fatty acid oxidation • with reference to its clinical disorders

  3. GLUCOSE HOMEOSTASIS DURING FASTING

  4. Triacylglycerol Fatty acids Glycerol FATTY ACID OXIDATION saturated fatty acid: CH3-(CH2)n-COOH unsaturated fatty acid: CH3-CH=CH-(CH2)n-COOH polyunsaturated fatty acid: CH3-CH=CH-CH2-CH=CH-(CH2)n-COOH CH2----OOC-R1 CH2OH HOOC-R1 | | R2-COO----CH CHOH + HOOC-R2  | CH2----OOC-R3 CH2OH HOOC-R3 Lipolysis General structures of fatty acids and triacylglycerol. Lipolysis of stored triacylglycerol by lipases produces fatty acids plus glycerol.

  5. MOBILIZATION OF STORED FATS LIPOLYSIS

  6. BETA-OXIDATION OF FATTY ACIDS • Major pathway for catabolism of FA • Consists of four reactions: shortening of FA by 2 carbons • Oxidation: produces FADH2 • Hydration: produces NADH • Thiolytic cleavage: produces 2 acetylCoA

  7. ACTIVATION OF FATTY ACIDS TO ACYL-COA FATTYACYL-COA SYNTHETASES (THIOKINASE) R-COO- + CoA + ATP + H20 Acyl CoA + AMP + 2Pi + 2H+

  8. CARNITINE • Lysine and Methionine • Liver and Kidney

  9. CLINICAL ASPECTS 1.CARNITINE DEFICIENCY: • Inadequate biosynthesis Liver disease Malnutrition(Strict vegetarian diet) • Increase requirement Pregnancy, Infections, Burns, Trauma • Losses can also occur in hemodialysis • SYMPTOMS: Hypoglycemia during fast 

  10. Palmitoylcarnitine respiratory chain Palmitoylcarnitine Palmitoyl-CoA FAD oxidation FADH2 H2O hydration NAD+ recycle 6 times oxidation NADH cleavage CoA CH3-(CH)12-C-S-CoA + Acetyl CoA Citric acid cycle O 2 CO2 Carnitine translocase inner mitochondrial membrane matrix side 2 ATP 3 ATP Processing and -oxidation of palmitoyl CoA

  11. ENERGY YIELD FROM ß-OXIDATION • From PalmitoylCoA ATP Yield 7NADH x 3 ATP by ETC oxidation 21 7 FADH2 x 2 ATP by ETC oxidation 14 8 Acetyl CoA x 12 ATP via Krebs CAC 96 Total (Gross) 131 ATP Less 2 ATP NET 129 ATP From one molecule of PalmitoylCoA

  12. MEDIUM CHAIN FATTY ACIDS Less than 12 Carbon SOURCE Milk INHERITED DEFECTS • Autosomal recessive • Defects in Medium-chain fatty acyl-CoA dehydrogenase CLINICAL FEATURES Hypoglycemia

  13. OXIDATION OF FA WITH ODD NUMBER OF CARBONS

  14. OXIDATION OF UNSATURATED FATTY ACIDS

  15. PEROXISOMES OXIDIZE VERY LONG CHAIN FATTY ACIDS • Very long chain fatty acids i.e.,C22. • FAD-containing Acyl CoA oxidase causes initial dehydrogenation ZELLWEGER'S SYNDROME Genetic defect VLCFA accumulate in Blood and tissues.

  16. α- OXIDATION OF FATTY ACIDS • α-oxidation by Phytanoyl COA α-Hydroxylase (PhyH) • Carbon 1 is released as CO2 • 19 Carbon Pristanic acid, is activated to it’s CoA derivative and undergoes β-Oxidation

  17. REFSUM'S DISEASE A rare neurologic disorder caused by accumulation of Phytanic acid. Inherited deficiency in α–oxidation. Symptoms are primarily neurologic.

  18. w- OXIDATION OF FATTY ACIDS • w-oxidation is a minor pathway forming a Dicarboxylic acid. They subsequently undergo ß-oxidation and are excreted in the urine.

  19. THANKS

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