Radical Reaction Control in the AdoMet Radical Enzyme CDG Synthase (QueE): Consolidate, Destabilize, Accelerate.

ABSTRACT: Controlling radical intermediates and thus catalysing and directing complex radical reactions is a central feature of S-adensosylmethionine (SAM)-dependent radical enzymes. We report ab initio and DFT calculations highlighting the specific influence of ion complexation, including Mg²⁺ , identified as a key catalytic component on radical stability and reaction control in 7-carboxy-7-deazaguanine synthase (QueE). Radical stabilisation energies (RSEs) of key intermediates and radical clock-like model systems of the enzyme-catalysed rearrangement of 6-carboxytetrahydropterin (CPH4), reveals a directing role of Mg²⁺ in destabilising both the substrate-derived radical and corresponding side reactions, with the effect that the experimentally-observed rearrangement becomes do

SUBMITTER: Jager CM 

PROVIDER: S-EPMC5347944 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature