Isotope LabelingDeuteriumDeuterium OxideDeuterium Exchange MeasurementIsotopesOxygen IsotopesNitrogen IsotopesCarbon IsotopesHydrogenMass SpectrometryBody WaterIndicator Dilution TechniquesMagnetic Resonance SpectroscopyZinc IsotopesRadioisotope Dilution TechniqueSulfur IsotopesKineticsIron IsotopesWaterSpectrometry, Mass, Electrospray IonizationGas Chromatography-Mass SpectrometryStrontium IsotopesModels, MolecularModels, ChemicalAmidesMolecular ConformationCatalysisProtein ConformationSolventsBody Fluid CompartmentsProtonsOxidation-ReductionStereoisomerismMethenamineHydrogen-Ion ConcentrationNuclear Magnetic Resonance, BiomolecularMolecular Structure