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Nitrate Reductases: There s more than one way to skin a snake or reduce a nitrate PowerPoint Presentation
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Nitrate Reductases: There s more than one way to skin a snake or reduce a nitrate

Nitrate Reductases: There s more than one way to skin a snake or reduce a nitrate

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Nitrate Reductases: There s more than one way to skin a snake or reduce a nitrate

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    1. Nitrate Reductases: Theres more than one way to skin a snake (or reduce a nitrate) Brad Bullock February 1, 2007

    2. General Information Nitrate reductases catalyze the reduction of nitrate: NO3- + 2H+ + 2e- -> NO2- + H2O Three classes in eubacteria respiratory membrane-bound (Nar) periplasmic (Nap) assimilatory cytoplasmic (Nas)

    3. Cofactors Hemes electron transfer to iron sulfur clusters Iron-sulfur clusters [3Fe-4S]1+,0 and [4Fe-4S]2+,1+ electron transfer to molybdenum Molybdopterin guanine dinucleotide surrounded by highly conserved regions -site of reduction

    4. Membrane-bound Nitrate Reductase (Nar) Ubiquinol oxidation releases two protons into the periplasm and two electrons into the protein The ?-helices of the ? subunit (25 kDa) anchor the ? (140 kDa) and ? (60 kDa) subunits to the cytoplasmic membrane Active site is on molybdenum Electron transfer pathway of 90 Expression of nar genes is induced by presence of nitrate

    5. Membrane-bound Nitrate Reductase: 1Q16