MolybdenumIsotopesPteridinesIsotope LabelingCoenzymesMetalloproteinsTungstenOxygen IsotopesNitrogen IsotopesCarbon IsotopesXanthine DehydrogenaseNitrate ReductasesAldehyde OxidaseNitrate ReductaseSulfite OxidasePterinsSulfurtransferasesXanthine OxidaseTungsten CompoundsOxidoreductases Acting on Sulfur Group DonorsNitrogenaseSulfur IsotopesSulfurNitrate Reductase (NADH)Zinc IsotopesAldehyde OxidoreductasesDeuteriumMolybdoferredoxinElectron Spin Resonance SpectroscopyRhodobacter capsulatusOxidoreductasesIron IsotopesMetal Metabolism, Inborn ErrorsFormate DehydrogenasesOxidation-ReductionIron-Sulfur ProteinsChloratesAzotobacter vinelandiiXanthineStrontium IsotopesAzotobacterKineticsSulfite DehydrogenaseNitrogen FixationOrganometallic CompoundsDesulfovibrio gigasRadioisotope Dilution TechniqueCatalysisDithioniteEscherichia coliMass SpectrometrySpectrophotometrySulfidesMetalloexopeptidasesTracheobiontaSulfitesTrace ElementsMilkChlorellaNitratesIndicator Dilution TechniquesFormatesMolecular Sequence DataIronMethanobacteriumNitrobacterNitrogenBacterial ProteinsHydrogen-Ion ConcentrationMetalsSeleniumHumic SubstancesRadioisotopesMolecular Structure