7 12 15 Biochemistry 401 Lecture 22 ATP Synthesis Uncouplers of Oxidative Phosphorylation Poisons of Oxidative Phosphorylation Energy released during electron transfer can be used to pump H into into the inter membrane space creating a proton concentration gradient and electrical potential across the inner membrane This is called chemiosmotic potential Chemiosmotic potential causes protons to flow flow back into the mitochondrial matrix which turns a turbine like molecular motor which helps to synthesize ATP Intermembrane Space Fo F1 Matrix http www pdb org pdb static do p education discussion molecule of the month pdb72 1 html 1 7 12 15 http www pdb org pdb static do p education discussion molecule of the month pdb72 1 html Central Shaft C Ring Stationary hexameric ring Central Shaft 3 3 Hexameric Ring 2 7 12 15 Neither half channel spans the membrane but instead abuts a c subunit Rotation depends on interactions between subunits c and a Intermembrane space High H H Matrix Low H ADP Pi ATP H Protons move down their concentration gradient powering ATP synthase Intermembrane Space Asp c Ring Matrix Aspartate in a proton poor environment Aspartic acid Proton rich environment Aspartic acid is neutral Can enter hydrophobic membrane 3 7 12 15 C Ring Asp Aspartate in a proton poor environment negative charge Aspartic acid in a proton rich environment neutral in charge Aspartic acid can enter the hydrophobic membrane 4 7 12 15 subunit is the site of ATP synthesis and has 3 conformations O Open Step 1 T Tense Step 2 L Loose Step 3 In the loose conformation ADP and Pi are bound but do not react In the Tense conformation ADP and Pi react to form ATP In the open conformation ATP is released 5 7 12 15 The subunit highlighted in yellow is in the tense conformation because of its interaction with the central subunit ATP is synthesized With rotation of the subunit 120 degrees clockwise the subunit highlighted in yellow is open a conformation that allows ATP release ATP is released allowing another ADP and Pi to bind ATP ADP Pi Step one ATP 6 7 12 15 Cyt c III I IV ATP synthase 7 7 12 15 Uncoupler I Cyt c III I III IV ATP synthase IV Azide CO and H2S ATP synthase Blocked by oligomycin I Rotenone Insecticide Amytal Barbiturate III Antimycin Antibiotic IV Cyanide Azide H2S Sewer gas and CO Azide CO and H2S ATP synthase Blocked by oligomycin Oligomycin Antibiotic 8 7 12 15 To help you P O ratio ATP produced per O2 reduced yielding H2O NADH 2 5 FADH2 1 5 H H H H H Cyt c III I IV ATP synthase Net molecules of ATP from Glycolysis 2 molecule of glucose 9 7 12 15 Total molecules of ATP from Glycolysis 2 molecule of glucose Total molecules of ATP from TCA cycle 2 molecule of glucose Net molecules of ATP from Glycolysis 2 molecule of glucose Total molecules of ATP from TCA cycle 2 molecule of glucose 4 26 Varies w shuttle Glycerol 3 P 30 Malate Aspartate 32 This marks the end of Lecture 22 Have a super day 10
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