23 - ATP - Control of ATP Synthesis. Antioxidants Learning...

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Control of ATP Synthesis. Antioxidants Coordinated control of oxidative metabolism The mechanism of ATP synthesis Advantages and disadvantages of the aerobic metabolism Cytochrome P450 Oxygen deprivation in the heart attack and stroke Learning Objectives Reactive oxygen species and antioxidants Uncoupling Electron Transport and Oxidative Phosphorylation
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Fig. 18-25 ATP Synthase, a Molecular Motor F 0 forms a wheel. F 1 consists of a rod with one end fixed to the wheel's hub. The other end of the rod is embraced by a bundle of six ! / " subunits. Protons pass via the mitochondrial membrane back to the matrix forcing the rod to rotate within the stationary bundle. The rotation provides a mechanical energy necessary to catalyze the endergonic combining of ADP and P i .
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Molecular Bearing Figure 18-22. Contacting surfaces of the rod and the wheel lack polar and ionogenic groups and contain predominantly hydrophobic residues that lubricate the bearing. One proton passing the F 0 channel swings F 1 by 120 0 . The synthesis of one ATP molecule from ADP and P i requires three protons to make a 360 0 turn of the rod. The 1997 Nobel prize was awarded to Paul Boyer and John Walker for their discovery of mechanism of ATP synthesis and to Jens Skou for his discovery of Na + /K + ATPase.
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Fig. 18-24 The Mechanism of ATP synthesis The three identical ! / " interfaces can adopt three different conformations. - Open conformation O does not bind ligands. - Catalytically inactive conformation L binds ligands loosely. - Catalytically active conformation T binds ligands tightly.
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Three-step ATP synthesis: - ADP and P i bind to site L; - Conformational transitions: L # T, T # O, and O # L; - ATP is synthesized at site T; ATP is released from site O. The energy for the conformational changes within the ! 3
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This note was uploaded on 02/06/2012 for the course BIOCHEM 2ee3 taught by Professor Zhorovb during the Spring '10 term at McMaster University.

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23 - ATP - Control of ATP Synthesis. Antioxidants Learning...

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