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Updated: Jun 24, 2026

Free Radicals in Chemical Biology: from Chemical Behavior to Biomarker Development
Published on: April 15, 2013
Product inhibition in the radical S-adenosylmethionine family
Martin R Challand1, Tillman Ziegert, Paul Douglas
1School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
Abstract:
Members of the radical S-adenosylmethionine (AdoMet) superfamily reductively cleave AdoMet to generate the highly reactive 5'-deoxyadenosyl radical (DOA()) which initiates biological transformations by abstraction of a hydrogen atom. We demonstrate that three members of the family: biotin synthase (BioB), lipoyl synthase (LipA) and tyrosine lyase (ThiH) are inhibited in vitro by a combination of the products 5'-deoxyadenosine (DOA) and methionine. These results suggest the observed inhibition is a common feature of the radical AdoMet proteins that form DOA and methionine as products. Addition of 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) to BioB, LipA or ThiH activity assays removed the product inhibition by catalysing the hydrolysis of DOA and gave an increase in activity.
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