LECTURE 8 - Ox-Phos overviewp 370 393Ox-Phos mitochondriap...

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Unformatted text preview: Ox-Phos - overviewp 370 - 393Ox-Phos - mitochondriap 370 - 393Outer membrane:-very porousInner membrane:>15-fold larger than outer membrane-impermeable to most small molecules-contains all the enzymes of e- transport and ox-phos-75% protein by massMatrix:-very gloopy (<50% water)-enzymes of citric acid cycleOx-Phos - “transporting NADH in”p 370 - 393Phase A: transport of e-into matrix-in cytosol, NADH reduces OAA to malate-malate is antiported for α-KG-in matrix, NAD+oxidizes malate to OAAPhase B: regeneration of cytosolic OAA-in matrix, a transaminase converts OAA to Asp (Glu --> α-KG)-Asp is antiported for Glu-in cytosol, a transaminase converts Asp to OAAOx-Phos - transporting ADP in/ATP outp 370 - 393ATP (4 negative charges) exchanged for ADP (3 negative charges)-ATP goes out, ADP comes in-an antiporter (it doesn’t change conformation unless ADP or ATP is bound)-not directly an active transport system-driven by membrane potential: negative inside, positive outside as set-up by e-transportSymport of Piand H+-electroneutral: negative Pi comes in with a positive H+-driven by pH gradient: lower pH on the outside as set-up by e-transportElectron transport - the playersNADH-a water soluble cofactor-not covalently attached to proteins-mostly does hydride transfer (2 e-at a time)Electron transport - the playersFADH2-a cofactor-tightly bound sometimes covalently to proteins = ¡avoproteins-can do one or two e- chemistryElectron transport - the playersubiquinone = coenzyme Q = Q-freely diffusible in lipids-can mediate one or two e-chemistry-also carries protonsElectron transport - the playerscytochromes-heme-containing proteins (a la hemoglobin)-hemes are tightly but not covalently bound-all do only one e-chemistry (Fe3+--> Fe2+)-subtle structural differences between hemes for different cytochromes-all are integral membrane proteins, except for cytochrome c, which associates with inner mitochondrial membrane via electrostaticsElectron transport - the playersIron sulfur proteins-contain Fe, S from cysteine, and/or S from inorganic sulfur-wide variety of structural con¡gurations possible-participate in chemistry of one e-at a timeOx-Phos - electrons “fow downhill”p 370 - 393Ox-Phos - complex Ip 370 - 393A proton pump driven by NADH oxidation-42 different polypeptides-one FMN-containing protein-at least 6 iron-sulfur clustersNADH + H++ Q ==> NAD++ QH2Ox-Phos - complex IIp 370 - 393Many ways to CoQ:-from NADH = complex I-from succinate = complex II...
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LECTURE 8 - Ox-Phos overviewp 370 393Ox-Phos mitochondriap...

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