A confluence of radical chemistry: S-Adenosylmethionine and Adenosylcob(III)alamin

Enzymes requiring adenosylcobalamin (AdoCbll) or complexes of [4Fe-4S] 1+ -S-adenosylmethionine (AdoMet) function with the intermediate formation of the 5'-deoxyadenosyl radical and catalyze reactions involving carbon-centered radical intermediates. The latter form the radical SAM superfamily and are far more numerous and catalyze much more chemically diverse reactions than the AdoCbl-enzymes. The radical SAM superfamily likely preceded the AdoCbl-enzymes in evolution.