Electrochemical properties of S-Adenosyl-L-Methionine and studies of a chimeric radical Sam enzyme-flavodoxin fusion protein

Members of the Radical SAM (RS) enzyme superfamily utilize the reductive capability of a coordinated [4Fe-4S] cluster to generate a chemically useful C-centered radical arising from the scission of S-adenosyl-L-methionine (SAM). In this dissertation, a dual approach towards following electron movements into both the [4Fe-4S] cluster and SAM itself were utilized. Characterization of the electrochemical properties of SAM in bulk solution showed homolysis occurs at a more permissive cathodic peak potential (Epc) -1.4V compared to previous literature estimates. Additionally, the biochemical and kinetic effects arising from the fusion of an activation domain to a catalytically competent domain were determined. Together these results have furthered the field by establishing an upper limit to the energetic requirement for the homolysis of SAM in bulk solution and the effects on [4Fe-4S] cluster +2/+1 reduction arising from activator proximity.