Lactose Tolerance TestHydrogenLactose IntoleranceBreath TestsHydrogen BondingHydrogen PeroxideHydrogen SulfideHydrogen CyanideModels, MolecularOxidantsCatalaseOxidation-ReductionDeuterium Exchange MeasurementCystathionine gamma-LyaseCrystallography, X-RayProtein ConformationHydrogenasePeroxidasesWaterHydrogen-Ion ConcentrationModels, ChemicalKineticsMolecular StructureMagnetic Resonance SpectroscopySulfidesThermodynamicsCatalysisMolecular Sequence DataBinding Sites