Artificial Metalloenzymes: From Selective Chemical Transformations to Biochemical Applications

Abstract

<jats:p>Artificial metalloenzymes (ArMs) comprise a synthetic metal complex in a protein scaffold. ArMs display performances combining those of both homogeneous catalysts and biocatalysts. Specifically, ArMs selectively catalyze non-natural reactions and reactions inspired by nature in water under mild conditions. In the past few years, the construction of ArMs that possess a genetically incorporated unnatural amino acid and the directed evolution of ArMs have become of great interest in the field. Additionally, biochemical applications of ArMs have steadily increased, owing to the fact that compartmentalization within a protein scaffold allows the synthetic metal complex to remain functional in a sea of inactivating biomolecules. In this review, we present updates on: (1) the newly reported ArMs, according to their type of reaction, and (2) the unique biochemical applications of ArMs, including chemoenzymatic cascades and intracellular/in vivo catalysis. We believe that ArMs have great potential as catalysts for organic synthesis and as chemical biology tools for pharmaceutical applications.</jats:p>

Chemical modifications of proteins and their applications in metalloenzyme studies

“…Among these metalloenzymes, non-heme iron (NHFe) and heme enzymes catalyze a remarkable range of chemical transformations, including hydroxylation, endoperoxidation, and desaturation at the expense of molecular oxygen as the final electron acceptor [ [99] , [100] , [101] , [102] ]. Recent efforts in utilizing these strategies in metalloenzyme engineering and their biochemical applications are summarized in several recent reviews [ 97 , [103] , [104] , [105] , [106] ]. This section presents selected case studies, from recent years, of NHFe, heme, and Cu-containing enzymes where ncAAs are used as novel tools.…”

Classifying metal‐binding sites with neural networks

“…Metalloenzymes are enzymes that contain at least one metal ion, and are found extensively in natural systems, with 40% of known enzyme structures containing metals (Andreini et al, 2008) and are an important aspect in many catalytic conversions (Fernandes et al, 2019; Holm et al, 1996; Warshel et al, 2006; Williams, 1971; Wolfenden and Snider, 2001). A significant amount of work has focused on creating artificial metalloenzymes because of the high specificity, selectivity, and ability of native metalloenzymes to function under mild conditions while employing non‐precious metals, as well as their potential to accelerate nonnatural reactions under mild conditions (Himiyama and Okamoto, 2020; Röthlisberger et al, 2008). Only a handful of design principles have been well established but, based on the often‐observed superior activity of enzymes over synthetic catalysts, more design principles have yet to be discovered.…”

Unnaturally Distorted Hexagonal Protein Ring Alternatingly Reorganized from Two Distinct Chemically Modified Proteins

“…Recruiting synthetic molecular components via chemical modification, often known as “post-translational mutagenesis”, has extended the limits of the functional and structural design of proteins from the conventional genetic manipulation-based mutagenesis of amino acid. − With the aid of a chemical toolbox inaccessible by nature, artificial enzymes, , protein assemblies, − and therapeutic biomaterials , have been developed by the selective tethering of functional molecules onto proteins. Indirect linkages between multiple proteins via chemical linkers have often been applied to construct artificial protein assemblies. − ,− To connect protein units by chemical modifications, covalent bonds and supramolecular interactions were constructed, between two artificially installed chemical tags or between the chemical tag and the pairing protein unit.…”