11H Complex I (NADH:ubiquinone oxidoreductase) and complex III (coenzyme Q: cytochrome c - oxidoreductase) each contain a 2Fe-2S iron sulfur cluster. However, the iron sulfur clusters have very distinct standard reduction potentials (E°). (i) Which iron-sulfur cluster can be expected to have a more positive standard reduction potential, 2Fe-2S in complex I or 2Fe-2S complex III? (ii) Briefly explain how it is possible for these 2Fe-2S iron sulfur clusters to have different E° values even though they have the same molecule structure?

11H Complex I (NADH:ubiquinone oxidoreductase) and complex III (coenzyme Q: cytochrome c - oxidoreductase) each contain a 2Fe-2S iron sulfur cluster. However, the iron sulfur clusters have very distinct standard reduction potentials (E°). (i) Which iron-sulfur cluster can be expected to have a more positive standard reduction potential, 2Fe-2S in complex I or 2Fe-2S complex III? (ii) Briefly explain how it is possible for these 2Fe-2S iron sulfur clusters to have different E° values even though they have the same molecule structure?

Biochemistry

6th Edition

ISBN:9781305577206

Author:Reginald H. Garrett, Charles M. Grisham

Publisher:Reginald H. Garrett, Charles M. Grisham

Chapter20: Electron Transport And Oxidative Phosphorylation

Section: Chapter Questions

Problem 11P

See similar textbooks

Similar questions

Energetics of the Hexokinase Reaction The standard-state free energy change. Gfor the hexokinase reaction, is â€” 1 6.7 kJ/mol. Use the values in Table I to calculate the value of Gfor this reaction in the erythrocyte at 37Â°C.
The standard reduction potential for ubiquione (A or coenzyme Q) is .045 V, and the standard reduciton potential (E) for FAD is -0.219 V. Using these values, show that the oxidation for FADH2 by ubiquinone theoretically liberates enough energy to drive the synthesis of ATP. Faraday constant =96.48KJ/Vol delta G' standard for ATP Synthesis is +30.5 KJ/mol R=8.314 J/mol K=1.987 cal/mol K
The inhibitor X prevents coenzyme Q (Q) from participating in electron transfer in the electrontransport chain.(a) Will the presence of X prevent electrons from N ADH from passing through the electron trans-port chain? Explain why or why not.(b) Compound Y is a non-physiological reducing agent capable of directly reducing cytochromec1 in Complex III. Would oxygen consumption resume upon the addition of compound Y tomitochondria inhibited by inhibitor X? Be sure to explain your answer.
Compare the delta ΔG0' values for the oxidation of succinate by NAD+ and by FAD. Use the data given in Table 18.1 to find the E0' of the NAD+-NADH and fumarate-succinate couples, and assume that E0' for the FAD – FADH2 redox couple is nearly 0.05 V. Why is FAD rather than NAD+ the electron acceptor in the reaction catalyzed by succinate dehydrogenase?
The half-reactions involved in the lactate dehydrogenase (LDH) reaction and their standard reduction potentials are (see attached)). Calculate ΔG at pH 7.0 for the LDH-catalyzed reduction of pyruvate under the following conditions: (a) [lactate]/[pyruvate] = 1 and [NAD+]/[NADH] = 1. (b) [lactate]/[pyruvate] = 160 and [NAD+]/[NADH] = 160. (c) [lactate]/[pyruvate] = 1000 and [NAD+]/[NADH] = 1000. (d) Discuss the eff ect of the concentration ratios in Parts a–c on the direction of the reaction.
In the complete b-oxidation of stearic acid (18:0) How many moles of FADH2 are produced? How many moles of ATP are produced after all NADH are reoxidized in the respiratory chain? How many moles of ATP are produced after all FADH2 are reoxidized in the respiratorychain? How many moles of ATP are produced from the complete oxidation of stearic acid?
The values of the reduction potential (Eº') of the conjugated redox pairs NAD+/NADH and pyruvate / lactate are -0'32 V and -0'19 V respectively. a) Which of the two conjugated pairs has a greater tendency to lose electrons? Reason for it. b) What is the strongest oxidizing agent? Reason for it. c) If we start with 1M concentrations of each reagent and product at pH 7.0 in which sense the reaction will pass pyruvate + NADH + H+ ⇄ lactate + NAD+ d) What is the standard free energy variation (ΔGº’ at 25ºC) for the conversion of pyruvate to lactate? e) What is the equilibrium constant of this reaction?
Describe the effects of (1) oligomycin and (2) uncouplers of oxidative phosphorylation, e.g., dinitrophenol (DNP), carbonyl cyanide-p- trifluoromethoxyphenylhydrazone (FCCP), on respiration and ATP synthesis when added to a suspension of mitochondria with excess malate, ADP, and inorganic phosphate (Pi).
A dialyzed pigeon liver extract will catalyze the conversion of acetyl-CoAto palmitate and CoASH if supplied with Mg2+, NADPH, ATP, HCO3-, andcitrate.(a) If H14CO3– is supplied, what compounds will become labeled (permanently or transiently) during the course of the reaction? In whatcompounds will 14C accumulate?(b) Explain the role of citrate in this reaction.
Begining with 1 M concentrations of each reactant and product at pH=7 and 25.0 degrees C, calculate the K'eq (to one decimal point) of the reaction Pyruvate + NADH+H+ <=> Lactate + NAD+.Note the temperature of this reaction will not affect the standard reducton potential delta E'o in the table 13-7b. please provide a comprehensive explanation with each step taken.
The enzyme dihydrofolate reductase (DHFR) normally resides in the cytosol, andDHFR can be imported into mitochondria by appending a mitochondrial signalsequence. However, when this modified DHFR is incubated with methotrexate, whichis a substrate analog that binds tightly to the active site, the modified DHFR is nolonger imported.a) Propose an explanation for why methotrexate prevents import of DHFR intomitochondria.b) Suppose that DHFR were modified instead by appending a nuclear localizationsignal. Would you expect methotrexate to prevent transport of this modified DHFRinto the nucleus? Why or why not?
Begining with 1 M concentrations of each reactant and product at pH=7 and 25.0 degrees C, calculate the K'eq of the reaction Pyruvate + NADH <=> Lactate + NADH+H+.Note the temperature of this reaction will not affect the standard reducton potential delta E'o in the table 13-7b.