Lipids Part 3b Pre-learning: Intro to Beta Oxidation PDF

Lipids Part 3b Prelearning: Intro to beta oxidation Dr. Rochelle Heisel BMS100 Beta Oxidation Once released from TG’s via lipolysis, ffa’s can be broken down for energy via beta oxidation First step: Activation of a fatty acid to a fatty acyl CoA + CoASH Fatty acid ATP Fatty acyl CoA CoA Beta Oxidat...

Lipids Part 3b Prelearning: Intro to beta oxidation Dr. Rochelle Heisel BMS100 Beta Oxidation Once released from TG’s via lipolysis, ffa’s can be broken down for energy via beta oxidation First step: Activation of a fatty acid to a fatty acyl CoA + CoASH Fatty acid ATP Fatty acyl CoA CoA Beta Oxidation Fatty acid activation (cytosol) Uses one ATP molecule, but the equivalent of two ATP’s worth of energy Hydrolysis to AMP and PPi first, then PPi hydrolysis 1) ATP 2) PPi AMP + PPi Pi + Pi 3) ATP ADP + Pi Fatty acid activation (1) and (2) together release approx. twice the amount of energy as (3), but only 1 ATP was used Beta Oxidation How do fatty acyl CoA’s get into the mitochondria? Require a carnitine transport system that involves: An enzyme to transfer the fatty acyl from CoA to a carnitine carrier (transferase - cytosol) A translocator to move the acyl-carnitine across the inner membrane and move free carnitine out (translocase) An enzyme to transfer the fatty acyl from carnitine back to CoA (transferase - matrix) Carnitine Shuttle Beta Oxidation Sequence Fatty Acyl CoA To CAC for energy Fatty Acyl CoA 2C shorter Acetyl CoA Beta Oxidation Energy Yield Determine the # of acetyl CoA by: § Dividing # of carbons by two Determine the # of cycles by: § Subtracting 1 from the number of acetyl CoA This equals the # of NADH and FADH2 Determine the energy from acetyl CoA via CAC § For each acetyl CoA that goes through CAC, you make: 3 NADH = 9 ATP § 1 NADH produces 3 ATP via ETC 1 FADH2 = 2 ATP § 1 FADH2 produces 2 ATP via ETC 1 GTP § Equivalent to 1 ATP 12 ATP via CAC for each acetyl CoA Subtract 2 ATP for fatty acid activation (making fatty acyl CoA) Check your knowledge To what is a fatty acid attached to become activated prior to beta-ox? Does this process make or use energy? How much? What carrier is used to take a fatty acyl across the inner mitochondrial membrane? Calculate the energy yield from a 16:0 fatty acid, assuming that all acetyl CoA molecules also go through CAC (answer to follow) Beta Ox Calculation Answer See next slide Energy Yield for 16:0 Fatty Acid Divide the number of C by 2 to get the # of acetyl CoA 16:0 produces 8 acetyl CoA Assuming the acetyl CoA goes into CAC, multiply by 12 to get the # of ATP (see next slide for CAC calculation) Divide the number of C by 2 and (-)1 to get the # of FADH2 & NADH: 16:0 produces 7 FADH2 & 7 NADH FADH2 - Multiply by 2 to get the # of ATP NADH - Multiply by 3 to get the # of ATP Add up all the ATP, and then subtract 2 Remember, it took 2 ATP to attach the fatty acid to the CoA molecule to make the fatty acyl group that enters beta ox Total: 129 ATP CAC calculation CAC makes: 3 NADH 1 NADH makes 3 ATP via the ETC 3 * 3 = 9 ATP 2 FADH2 1 FADH2 makes 2 ATP via the ETC 2 * 2 = 2 ATP 1 ATP (via GTP) Total ATP for 1 acetyl CoA: 9 + 2 + 1 = 12