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Fat Metabolism. I’m not fat, I’ve just got a lot of potential energy!. Digestion, Mobilization, and Transport. http://courses.cm.utexas.edu/emarcotte/ch339k/fall2005/Lecture-Ch17-1/Slide2.JPG. Emulsification. Fats are not water soluble Made into bile salts that are
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Fat Metabolism I’m not fat, I’ve just got a lot of potential energy!
Digestion, Mobilization, and Transport • http://courses.cm.utexas.edu/emarcotte/ch339k/fall2005/Lecture-Ch17-1/Slide2.JPG
Emulsification • Fats are not water soluble • Made into bile salts that are • Absorbed as micelles in small intestines
Chylomicron Carriers • proteins that carry fats • stored in adipose tissue
Role of Hormones • Can mobilize from adipose • Release as Fatty acids • Epinephrene and glucagon release cAMP • make fatty acids and glycerol • mobilizes fat
Animation of Process • http://www.wiley.com/legacy/college/boyer/0470003790/animations/fatty_acid_metabolism/fatty_acid_metabolism.htm • FUN!
Activation and Transported to Mitochondria • FA + CoASH --> ATP = FA-SCoA + AMP + Ppi • Driven by breakup of Ppi • Acyl CoA Synthetase • -32.5 kJ • Transported through inner mitochondrial membrane via carnitine • uses specific acyl carnitine transporter
Formation of acyl carnitine • Can get transported across inner mitochondrial membrane
Animation of Process • http://www.brookscole.com/chemistry_d/templates/student_resources/shared_resources/animations/carnitine/carnitine1.html
Beta Oxidation • Breakdown of fats into • Acetyl coenzyme A --> Krebs Cycle • FADH2 --> Oxidative Phosphorylation • NADH--> Oxidative Phosphorylation • Breaks off two carbons at a time to acetyl CoA • Remaining goes another round
Reactions of Beta Oxidation Acyl-CoA Dehydrogenase • Puts in a ß double bond • Oxidizes C-C bond to double bond • Produces FADH2
Reactions of Beta oxidationEnoyl CoA Hydratase • adds water • forms ß-hydroxy product
Reactions of Beta Oxidation ß-hydroxylacyl-CoA dehydrogenase • oxidizes secondary alcohol to ketone • Oxygen-containing group • Produces NADH
Reactions of Beta Oxidation Acyl-CoA acetyltransferase (thiolase) • Uses another CoA • Produces Acetyl CoA • Acyl CoA can go another round
Overall Per Beta Oxidation cycle • 1 FADH2…………………………1.5 ATP • 1 NADH………………………….2.5 ATP • 1 Acetyl CoA to Krebs • 3 NADH X 2.5 ATP / NADH………7.5 ATP • 1 FADH2…………………………….1.5 ATP • 1 GTP………………………………..1.0 ATP Total =14.0 ATP
Beta Oxidation on 16 C fatty Acid • 7 rounds of Beta oxidation (bottom numbers) • Form 8 acetyl Co A (top numbers)
Beta Oxidation on 16 C fatty Acidtotals • 7 rounds of beta oxidation 7 rounds X FADH2 X 1.5 ATP = 10.5 ATP round FADH2 7 rounds X NADH X 2.5 ATP = 17.5 ATP round NADH 8 acetyl CoA 8 Krebs 8 Krebs X 3 NADH X 2.5 ATP = 60 ATP Krebs NADH 8 Krebs X FADH2 X 1.5 ATP = 12 ATP Krebs FADH2 8 Krebs X GTP X 1 ATP = 8 ATP Krebs GTP 1 ATP used to activate = - 1 ATP Total 107 ATP
Unsaturated Fat Metabolism • special enzymes needed to convert cis bonds in fatty acids to trans bonds
Regulation of Fat Metabolism • Transport is rate-limiting • Regulation of carnitine acyl transferase • off by fat synth products • high NADH
Ketone Bodies • Starvation causes accumulation of acetyl CoA • not enough carbohydrates to keep Kreb’s Cycle going • acetyl CoA forms acetoacetate, b-hydroxybutyrate, and acetone. • http://www.biocarta.com/pathfiles/ketonebodiesPathway.asp
Diabetes and Ketone Bodies • When there is not enough insulin in the blood and it must break down fat for its energy. • Ketones build up in the blood and then spill over into the urine so that the body can get rid of them. Acetone can be exhaled through the lungs. This gives the breath a fruity odor. Ketones that build up in the body for a long time lead to serious illness and coma. (Diabetic ketoacidosis)
Comparison of Fat Metabolism per gram and CHO per gram • Fats provide about 9 kilocalories per gram and carbohydrates provide about 4 kilocalories per gram. • Using nutritional units, that is 9 Calories/gram for fats and 4 Calories/gram for carbohydrates. • CHO provide energy more quickly • Fats are good fuel for endurance events, but not sprints