Characterization of Radical S-adenosylmethionine Enzymes and Intermediates in their Reactions by Continuous Wave and Pulse Electron Paramagnetic Resonance Spectroscopies

Radical S-adenosylmethionine (SAM) enzymes comprise an important and a versatile superfamily of enzymes. For more than a decade, a significant effort has been directed towards understanding these enzymes. Electron paramagnetic resonance spectroscopy has played a crucial role in such studies, helping to decipher intricate details about the identity of the active metallocofactors, their relations to the substrate(s) utilized and an understanding of the mechanisms of the enzymatic reactions. In this chapter we overview research milestones in the field of radical SAM enzymes achieved with the aid of EPR spectroscopy.