Origin and Control of Chemoselectivity in Cytochrome c-Catalyzed Carbene Transfer into Si–H and N–H bonds

25 February 2021, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


A cytochrome c heme protein was recently engineered to catalyze the formation of carbon–silicon bonds via carbene insertion into Si–H bonds, a reaction that was not previously known to be catalyzed by a protein. High chemoselectivity towards C–Si bond formation over competing C–N bond formation was achieved, although this trait was not screened for during directed evolution. Using computational and experimental tools, we now establish that activity and chemoselectivity are modulated by conformational dynamics of a protein loop that covers the substrate access to the iron-carbene active species. Mutagenesis of residues computationally predicted to control the loop conformation altered the protein’s chemoselectivity from preferred silylation to preferred amination of a substrate containing both N–H and Si–H functionalities. We demonstrate that information on protein structure and conformational dynamics, combined with knowledge of mechanism, leads to understanding of how non-natural and selective chemical transformations can be introduced into the biological world.


Directed Evolution
Chemoselective carbene transfer reactions
MD simulations

Supplementary materials

SI SiH NH chemoselectivity 20210224


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