newlecture12

newlecture12 - 17-1Electron Transport ChainElectron...

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Unformatted text preview: 17-1Electron Transport ChainElectron Transport Chain22 H2O+4 H++4 e-O217-2Electron Transport ChainElectron Transport ChainProton gradient across inner mitochondrial membrane17-3the proton gradientestablishes avoltage gradientthe proton and voltage gradients together provide the mechanism to couple electron transport with phosphorylation of ADP+ADPPiATP+H2OElectron Transport ChainElectron Transport Chain17-4Electron Transport ChainElectron Transport ChainThe electron transport chainthis oxidation results information of 2.5 ATPthis oxidation results in formation of 1.5 ATP17-5Reduction PotentialsReduction PotentialsA useful way to look at electron transport is to consider the change in free energy associated with the movement of electrons from one carrier to anotherif we have two electron carriers, for example NADH and coenzyme Q, are electrons more likely to be transferred from NADH to coenzyme Q, or vice versa?what we need to know is the reduction potentialreduction potentialfor each carriera carrier of high reduction potential will tend to be reduced if it is paired with a carrier of lower reduction potential17-6Reduction PotentialsReduction PotentialsTable 17.1 Standard reduction potentialsincreasingreductionpotentials17-7NADH-CoQ oxidoreductaseelectrons are passed from NADH (low) to FMN (high)NNH3CH3CNNHOOCH2CH2OPO32 -Flavin mononucleotide(FMN)NNH3CH3CNNHOOCH2CH2OPO32 -Dihydroflavin mononucleotide(FMNH2)HH2 H+ + 2 e-( CHOH)3( CHOH)3Protons picked up andDelivered to inner mitochondrial space17-8Complex IComplex Ielectrons are then passed to the iron-sulfur clustersfinally, electrons are passed to coenzyme Q(also called ubiquinone)CH3OCH3O( CH2CH= CCH2)nCH3OOCH3HCoenzyme Q(oxidized form)CH3OCH3O( CH2CH= CCH2)nCH3OHOHCH3HCoenzyme QH2(reduced form)reductionoxidation2 H+ + 2 e-+Protons picked up andDelivered to inner mitochondrial space17-9Complex IComplex Ithe overall equation for the reaction of complex I isthis transfer drives proton pumpingthis transfer of electrons is strongly exergonicand is sufficient to drive phosphorylation of ADPE-FMNH2+2 Fe -S( o x)E-FMN2 Fe -S( re d)+2 H++Fe -S( re d)+ Co Q2 H++Fe -S( o x)+ Co QH2NADH+H++ E-FMNNAD++ E-FMNH2NADH+H++ Co QNAD++ Co QH2220d=-81-1G' = +30.5 kJmol-1ADP+Pi+ H2OATP17-10...
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newlecture12 - 17-1Electron Transport ChainElectron...

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