The Elusive 5'-Deoxyadenosyl Radical: Captured and Characterized by Electron Paramagnetic Resonance and Electron Nuclear Double Resonance Spectroscopies.

ABSTRACT: The 5'-deoxyadenosyl radical (5'-dAdo·) abstracts a substrate H atom as the first step in radical-based transformations catalyzed by adenosylcobalamin-dependent and radical S-adenosyl-l-methionine (RS) enzymes. Notwithstanding its central biological role, 5'-dAdo· has eluded characterization despite efforts spanning more than a half-century. Here, we report generation of 5'-dAdo· in a RS enzyme active site at 12 K using a novel approach involving cryogenic photoinduced electron transfer from the [4Fe-4S]⁺ cluster to the coordinated S-adenosylmethionine (SAM) to induce homolytic S-C5' bond cleavage. We unequivocally reveal the structure of this long-sought radical species through the use of electron paramagnetic resonance (EPR) and electron nuclear double resonance

SUBMITTER: Yang H 

PROVIDER: S-EPMC6784836 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature