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Radical Stabilization Energies for Enzyme Engineering – Tackling the Substrate Scope of the Radical Enzyme QueE

Suess, Christian; Martins, Floriane; Croft, Anna; Jaeger, Christof

Authors

Christian Suess

Floriane Martins



Abstract

Experimental assessment of catalytic reaction mechanisms and profiles of radical enzymes can be severely challenging due to the reactive nature of the intermediates, and sensitivity of cofactors such as iron sulfur clusters. Here we present an enzyme-directed computational methodology for the assessment of thermodynamic reaction profiles and screening for radical stabilization energies (RSEs) for the assessment of catalytic turnovers in radical enzymes. We have applied this new screening method to the radical SAM enzyme CPH4 synthase (QueE), following a detailed molecular dynamics (MD) analysis that clarifies the role of both specific enzyme residues and bound Mg2+, Ca2+ or Na+. The MD simulations provided the basis for a statistical approach to sample different conformational outcomes. RSE calculation at the M06-2X/6-31+G* level of theory provided the most computationally cost-effective assessment of enzyme-based energies, facilitated by an initial triage using semi-empirical methods. The impact of intermolecular interactions on RSE was clearly established and application to the assessment of potential alternative substrates (focusing on radical clock type rearrangements) proposes a selection of carbon-substituted analogues that would react to afford cyclopropylcarbinyl radical intermediates, as candidates for catalytic turnover by QueE.

Journal Article Type Article
Print ISSN 1549-9596
Electronic ISSN 1549-960X
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
APA6 Citation Suess, C., Martins, F., Croft, A., & Jaeger, C. (in press). Radical Stabilization Energies for Enzyme Engineering – Tackling the Substrate Scope of the Radical Enzyme QueE. Journal of Chemical Information and Modeling, https://doi.org/10.1021/acs.jcim.9b00017
DOI https://doi.org/10.1021/acs.jcim.9b00017
Publisher URL https://pubs.acs.org/doi/abs/10.1021/acs.jcim.9b00017
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