Trapping and Electron Paramagnetic Resonance Characterization of the 5'dAdo^• Radical in a Radical S-Adenosyl Methionine Enzyme Reaction with a Non-Native Substrate.

ABSTRACT: S-Adenosyl methionine (SAM) is employed as a [4Fe-4S]-bound cofactor in the superfamily of radical SAM (rSAM) enzymes, in which one-electron reduction of the [4Fe-4S]-SAM moiety leads to homolytic cleavage of the S-adenosyl methionine to generate the 5'-deoxyadenosyl radical (5'dAdo^•), a potent H-atom abstractor. HydG, a member of this rSAM family, uses the 5'dAdo^• radical to lyse its substrate, tyrosine, producing CO and CN that bind to a unique Fe site of a second HydG Fe-S cluster, ultimately producing a mononuclear organometallic Fe-l-cysteine-(CO)₂CN complex as an intermediate in the bioassembly of the catalytic H-cluster of [Fe-Fe] hydrogenase. Here we report the use of non-native tyrosine substrate analogues to further probe the initial

SUBMITTER: Sayler RI 

PROVIDER: S-EPMC6891858 | biostudies-literature | 2019 Nov

REPOSITORIES: biostudies-literature