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Direct observation of a deoxyadenosyl radical in an active enzyme environment
Author(s) -
Heidinger Lorenz,
Kneuttinger Andrea C.,
Kashiwazaki Gengo,
Weber Stefan,
Carell Thomas,
Schleicher Erik
Publication year - 2016
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1002/1873-3468.12498
Subject(s) - chemistry , radical , enzyme , electron paramagnetic resonance spectroscopy , electron paramagnetic resonance , biocatalysis , photochemistry , active site , density functional theory , catalysis , stereochemistry , reaction mechanism , computational chemistry , organic chemistry , nuclear magnetic resonance , physics
5′‐deoxyadenosyl radicals have been proposed as the first common intermediate in the molecular reaction mechanism of the family of radical S ‐adenosyl ‐l ‐methionine (SAM) enzymes. However, this radical species has not yet been directly observed in a catalytically active enzyme environment. In a reduced and SAM‐containing C140A mutant of the spore photoproduct lyase from Geobacillus thermodenitrificans , a mutant with altered catalytic activity, we were able to identify an organic radical with pronounced hyperfine structure using electron paramagnetic resonance spectroscopy. Guided by quantum‐chemical computations at the density functional theory level of theory, this radical could be tentatively assigned to a deoxyadenosyl radical, which provides first experimental evidence for this intermediate in the reaction mechanism of radical SAM enzymes.