Chapter_18

Chapter_18 - Click to edit Master subtitle style Chapter 18...

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Unformatted text preview: Click to edit Master subtitle style Chapter 18 Oxidative Phosphorylation LSU Undergraduate Summer Research Scientific Research Life Sciences and Chemistry $3500 stipend & program housing College credit http://www.biology.lsu.edu/hhmiprog/u ndergrad/ Program Dates May 31 July 30, 2010 Application Deadline Feb 10, 2010 For more information contact Sheri Wischusen 225-578- 0405 hhmi@lsu.edu Oxidative phosphorylation Oxidative phosphorylation I. Oxidative phosphorylation in eukaryotes takes place in mitochondria 1. Mitochondria -- 2 m in length and 0.5 m in diameters. 2. Contains enzymes of the citric acid cycle and of fatty acid oxidation 3. Outer membrane; inner membrane -- cristae; 4. The intermembrane space between the outer membrane and the inner membrane; -- oxidative phosphorylation 5. The matrix -- the citric acid cycle and fatty acid oxidation. Outer membrane -- VDAC -- open for PO4, Cl- organic anions. Inner membrane -- various transporters to shuffle small molecules; Matrix (N) -- Cytosol (P) Mitochondria resemble a microbial symbiant: the All protein coding genes found in all sequenced mitochondrial genomes are contained in Reclinomonas Oxidative phosphorylation depends on electron transfer I. High energy electrons -- redox potentials and free-energy changes: The reduction potential X- + H+ ----> X +0.5H2 X- ----> X + e- ; H+ + e- ----> 0.5H2 negative potential ==> electron donor positive potential ==>electron acceptor Go = -nF Eo F == Faraday constant ==23.06 kcal/mol/V Potential difference measured at beginning of experiment 1 M oxidant, 1 M reductant, 1 M H+, 1 M H2 Redox potential of H+/H2 pair = 0 Oxidative phosphorylation depends on electron transfer I. High energy electrons -- redox potentials and free-energy changes Pyruvate + NADH +H + <====> lactate + NAD+ Pyruvate + 2H+ + 2e- ----> lactate Eo = -0.19V NAD+ + 2H+ + 2e- ----> NADH Eo = -0.32V Pyruvate + 2H+ + 2e- ----> lactate Eo = -0.19V NADH -------->NAD+ + 2H+ + 2e- Eo = +0.32V G0(top)= +8.8 kcal/mol G0(bottom)= -14.8 kcal/mol G0(total) =8.8 -14.8 = -6.0 kcal/mol Oxidative phosphorylation depends on electron transfer II. NADH and O2 drives electron transport 1/2 O2 + NADH +H + <====> H2O + NAD+ 1/2 O2 + 2H+ + 2e- ----> H2O Eo = +0.82 V NAD+ + 2H+ + 2e- ----> NADH Eo = -0.32V G0(total) =-52.60 kcal/mol Substantial amount of energy; Hydrolysis of ATP will release -7.3 kcal/mol For the inner mictochondrial membrane (typlically) pH out ~ pH in 1.4, & V ~ 0.14 V Proton transported out of the matrix to cytoplasm ~5.2 kcal/mol The Respiratory chain consists of four complexes...
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This note was uploaded on 09/13/2010 for the course BIOL 4087 taught by Professor Waldrop during the Spring '08 term at LSU.

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Chapter_18 - Click to edit Master subtitle style Chapter 18...

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