If It Is Hard, It Is Worth Doing: Engineering Radical Enzymes from Anaerobes

Abstract

With a pressing need for sustainable chemistries, radical enzymes from anaerobes offer a shortcut for many chemical transformations and deliver highly sought-after functionalizations such as late-stage C–H functionalization, C–C bond formation, and carbon-skeleton rearrangements, among others. The challenges in handling these oxygen-sensitive enzymes are reflected in their limited industrial exploitation, despite what they may deliver. With an influx of structures and mechanistic understanding, the scope for designed radical enzymes to deliver wanted processes becomes ever closer. Combined with new advances in computational methods and workflows for these complex systems, the outlook for an increased use of radical enzymes in future processes is exciting.

Study and design of amino acid-based radical enzymes using unnatural amino acids

“…Structure-function relationship can be established from examination of knowledge accumulated from native enzyme studies, further facilitate engineering of radical enzymes for synthetic applications. 21,115,116 General computational methods such as molecular dynamics, quantum mechanics-molecular mechanics simulation, and more specialized tool to calculate radical stabilization energies also greatly facilitates the engineering process. [117][118][119] Integration of these methods leads to a workflow for radical enzyme identification and validation proposed by Ja ¨ger and Croft.…”

“…[117][118][119] Integration of these methods leads to a workflow for radical enzyme identification and validation proposed by Ja ¨ger and Croft. 116 De novo design [120][121][122] or redesign 123,124 of radical enzymes can create radical-containing models with a simple scaffold and/or mimic the structural features and function of the native enzymes, making it an complementary approach to study the native radical enzymes. a3 as a system to study the amino acid radicals in a protein environment.…”

“…117–119 Integration of these methods leads to a workflow for radical enzyme identification and validation proposed by Jäger and Croft. 116…”

Application of a Synthetic Ferredoxin‐Inspired [4Fe4S]‐Peptide Maquette as the Redox Partner for an [FeFe]‐Hydrogenase

“…[1][2] Hosting several types of FeS clusters, including [2Fe2S], [3Fe4S], [4Fe3S], and [4Fe4S], [3][4][5][6] these proteins act as redox mediators within metabolic, respiratory, and photosynthetic electron transport pathways, and catalyze a broad range of synthetically challenging chemistry. [7][8][9][10][11] Due to their central importance within bacterial metabolism, FeS proteins are postulated to have played a role in the origins of life on Earth in early prokaryotes (the iron-sulfur-world hypothesis). [12][13] The 'bacterial-type' ferredoxins host a [4Fe4S] 2 + / + cluster consisting of Fe 2 + and Fe 3 + ions linked in a cubic structure by four sulfide anions, and coordinated by the thiolate sidechains of four ligand cysteine (Cys) residues.…”

“…[ 1 , 2 ] Hosting several types of FeS clusters, including [2Fe2S], [3Fe4S], [4Fe3S], and [4Fe4S],[ 3 , 4 , 5 , 6 ] these proteins act as redox mediators within metabolic, respiratory, and photosynthetic electron transport pathways, and catalyze a broad range of synthetically challenging chemistry. [ 7 , 8 , 9 , 10 , 11 ] Due to their central importance within bacterial metabolism, FeS proteins are postulated to have played a role in the origins of life on Earth in early prokaryotes (the iron‐sulfur‐world hypothesis). [ 12 , 13 ]…”