Non-Native Site-Selective Enzyme Catalysis

Abstract

The ability to site-selectively modify equivalent functional groups in a molecule has the potential to streamline syntheses and increase product yields by lowering step counts. Enzymes catalyze site-selective transformations throughout primary and secondary metabolism, but leveraging this capability for non-native substrates and reactions requires a detailed understanding of the potential and limitations of enzyme catalysis and how these bounds can be extended by protein engineering. In this review, we discuss representative examples of site-selective enzyme catalysis involving functional group manipulation and C–H bond functionalization. We include illustrative examples of native catalysis, but our focus is on cases involving non-native substrates and reactions often using engineered enzymes. We then discuss the use of these enzymes for chemoenzymatic transformations and target-oriented synthesis and conclude with a survey of tools and techniques that could expand the scope of non-native site-selective enzyme catalysis.

Selective P450BM3 Hydroxylation of Cyclobutylamine and Bicyclo[1.1.1]pentylamine Derivatives: Underpinning Synthetic Chemistry for Drug Discovery

“…Direct hydroxylation of CBA and BCPA cores provides difunctionalized templates from which selective transformations of either the protected amine or the free alcohol functionality can lead rapidly to diverse small-molecule collections . As summarized in Scheme , the newly introduced hydroxyl group in (1 S ,2 S )- 14 is compatible with removal of the Boc group and N-acylation to give, in this case, a substrate 30 for potential elaboration by cross-coupling chemistry.…”

Identifying and Engineering Flavin Dependent Halogenases for Selective Biocatalysis

“…48 No changes in selectivity were observed during our substrate scope evolution, 39 indicating that either such changes were not occurring or our UPLC assays could not detect them. More broadly, efforts to alter the site selectivity of enzymatic C-H functionalization were rare at the time we initiated our efforts, 6,9 and the successful examples in the literature did not involve direct screens for altered selectivity 50 .…”

“…General and rapid means to tune binding so that different substrates and sites/functional groups on those substrates can react selectively must be developed. 9 When I started my independent research group, several features of flavin dependent halogenases (FDHs) suggested that they could be amenable to these requirements (Figure 1C). [10][11][12][13] The tryptophan halogenases PyrH, 14 Thal, 15 and PrnA 16 were known to selectively halogenate tryptophan at its 5-, 6-, or 7-position, respectively.…”

Unusual catalytic strategy by non-heme Fe(ii)/2-oxoglutarate-dependent aspartyl hydroxylase AspH

“…46–49 In contrast to small molecule catalysts, enzymes can be continuously optimized, redesigned and repurposed for performing specific C–H reactions with industrial importance. 50–52 Residues in the Second Coordination Sphere (SCS) and Remote Areas (RA) became increasingly important tools for modulating and improving enzyme activity and product selectivity. 53–59…”