Sulfonium‐Based Homolytic Substitution Observed for the Radical SAM Enzyme HemN

Abstract

Figure 5. A model sulfonium-based S H reaction. A) Photolysis reaction of dimethyl 2-(o-iodophenyl)ethyl sulfonium (8). B) HPLC analysis of the standard 8 (i), the photolysis reaction mixture of 8 (ii), and synthetic standard of 10 treated with the same reaction conditions as for the photolysis of 8 (iii). UV absorbance was measured at 254 nm. Angewandte ChemieCommunications 8883

Radical SAM‐Dependent Demetallation of Heme

“…[ 1‐6 ] In most cases, dAdo radical abstracts a hydrogen atom from the substrate to initiate highly diverse reactions. [ 1‐6 ] The dAdo radical can also add to sp 2 carbons [ 7‐10 ] or heteroatoms [ 11‐14 ] to result in an adenosylation reaction. Although in general, radical SAM enzymes have evolved dedicated microenvironments to finely control the reactivity of intermediates to achieve a specific catalytic outcome, promiscuous activities leading to off‐pathway shunt products have been observed for several enzymes, [ 15‐20 ] highlighting the remarkable catalytic plasticity of this superfamily of enzymes.…”

Consecutive Methylation Catalyzed by TsrM, an Atypical Class B Radical SAM Methylase

“…In most cases, dAdo radical abstracts a hydrogen atom from the substrate to produce 5ˊ‐deoxyadenosine (dAdoH) and a substrate radical, thereby initiating highly diverse reactions. [ 2‐3 ] The dAdo radical can also add to sp 2 carbons [ 4‐8 ] or heteroatoms [ 9‐12 ] to result in adenosylation reactions. Although in general radical SAM enzymes have evolved dedicated microenvironments to tune the reactivity of intermediates to achieve a specific catalytic outcome, promiscuous reactions have been observed in various systems, [ 13‐25 ] highlighting the remarkable catalytic plasticity of this superfamily of enzymes.…”