X-Ray Absorption SpectroscopySpectrometry, X-Ray EmissionSpectrum AnalysisX-RaysFourier AnalysisMetalloproteinsZincElectron Probe MicroanalysisIronMagnetic Resonance SpectroscopyAbsorptionIntestinal AbsorptionSpectroscopy, MossbauerCopperElectron Spin Resonance SpectroscopySpectrum Analysis, RamanManganeseSulfurModels, MolecularBinding SitesFerric CompoundsAbsorptiometry, PhotonOxygenMolecular StructureMolecular ConformationOrganometallic CompoundsWaterProtein ConformationOxidation-Reduction