S-AdenosylmethioninePQQ CofactorBiocatalysisFree RadicalsIron-Sulfur ProteinsBacterial ProteinsModels, MolecularSulfurtransferasesIntramolecular TransferasesMethyltransferasesOxidation-ReductionHydroxyl RadicalCoenzymesFree Radical ScavengersQuinolonesHeparin Cofactor IIGlucose 1-DehydrogenaseElectron Spin Resonance SpectroscopyPteridines