PorphyrinsCoproporphyrinsMetalloporphyrinsNitrogen FixationHematoporphyrinsPorphyriasUroporphyrinsProtoporphyrinsDeuteroporphyrinsAminolevulinic AcidNitrogen IsotopesNitrogen CompoundsNitrogen CycleMesoporphyrinsBlood Urea NitrogenNitrogen DioxideHemeHarderian GlandFerrochelataseHematoporphyrin DerivativePhotosensitizing AgentsPhotochemotherapyReactive Nitrogen SpeciesLevulinic AcidsDihematoporphyrin EtherPorphyrinogensNitrogen OxidesPorphobilinogenPII Nitrogen Regulatory ProteinsUroporphyrinogen DecarboxylaseNitratesCarbonHydroxymethylbilane SynthaseHeminAmmoniaHexachlorobenzeneFertilizersSpectrophotometryHemeproteinsSpectrometry, Fluorescence5-Aminolevulinate SynthetaseQuaternary Ammonium CompoundsMolecular StructureOxidation-ReductionPorphyria Cutanea TardaIronUroporphyrinogensPorphyrias, HepaticDicarbethoxydihydrocollidineProtoporphyrinogen OxidaseGlutamate-Ammonia LigasePorphobilinogen SynthaseMyoglobinKineticsLightUreaSpectrum AnalysisSoilAmino AcidsNitrogen Mustard CompoundsHematoporphyrin PhotoradiationPhotochemistryOxygenHydrogen-Ion ConcentrationNitrogenaseCobaltGold CompoundsElectronsSpectrophotometry, UltravioletManganeseSpectrum Analysis, RamanSymbiosisLyasesChromatography, High Pressure LiquidPeroxidasesGriseofulvinChlorophyll