Nitrogen IsotopesMolecular StructureNitrogen FixationHydrogen BondingStructure-Activity RelationshipModels, MolecularNitrogenCoordination ComplexesCrystallography, X-RayMolecular ConformationAminesAminationMagnetic Resonance SpectroscopyNitrogen CompoundsStereoisomerismBinding SitesChemical PhenomenaNitrogen CycleModels, ChemicalBlood Urea NitrogenNitrogen DioxideChemistryEstersQuaternary Ammonium CompoundsElectron Spin Resonance SpectroscopyHistidineCopperCatalysisProtein ConformationOxidation-ReductionQuantum TheoryReactive Nitrogen SpeciesHydrogen-Ion ConcentrationSpectrophotometryPhysicochemical PhenomenaKineticsAmidesSpectrum AnalysisOrganometallic CompoundsChemistry, PhysicalIndicators and ReagentsProtonsMolecular Sequence DataNitrogen OxidesProtein BindingMass SpectrometryPII Nitrogen Regulatory ProteinsSpectrometry, Mass, Electrospray IonizationOxygenCarbonAmino Acid SequenceLigandsThermodynamicsImidazolesAmmoniaNitratesFertilizersSpectrometry, Mass, Fast Atom BombardmentGlutamate-Ammonia LigaseAmino AcidsUreaNitrogenaseSoilNitrogen Mustard CompoundsSulfurSymbiosisBiomassBacterial ProteinsGlutamineAcetylenePlant RootsHydrogenWaterPlant LeavesDigestionPhosphorusCulture MediaGene Expression Regulation, BacterialAmmonium CompoundsNitritesGlutamate SynthaseAllantoinOxygen IsotopesNitrate ReductaseRoot Nodules, PlantCyanobacteriaCarbon IsotopesOxidoreductasesIronDenitrificationPoaceaeBacteriaPhotosynthesisGenes, BacterialEcosystemMutationKetoglutaric AcidsAnimal FeedEscherichia coliProteins