Enzymatic site-selectivity enabled by structure-guided directed evolution

Abstract

Biocatalytic site-selective (regioselective) organic transformations have been practiced for decades, but the traditional limitations of enzymes regarding narrow substrate acceptance and the often observed insufficient degree of selectivity have persisted until recently. With the advent of directed evolution, it is possible to engineer site-selectivity to suit the needs of organic chemists. This review features recent progress in this exciting research area, selected examples involving P450 monooxygenases, halogenases and Baeyer-Villiger monooxygenases being featured for illustrative purposes. The complementary nature of enzymes and man-made catalysts is emphasized.

Biocatalytic Oxidation Reactions: A Chemist's Perspective

“…Hence,B VMO-mediated Baeyer-Villiger oxidations give access to products inaccessible by chemical pathways.F urthermore,e ven if ag iven enzyme does not reach the desired selectivity,itcan be engineered. [142] Amongst the numerous examples demonstrating how BVMO engineering can be applied to obtain both the "normal" and the "abnormal" lactone products,two examples reported by the Reetz and Bornscheuer groups should be mentioned here.Using CHMO as the catalyst, Reetz and coworkers achieved the discrimination of E/Z-configured, trisubstituted alkenes containing keto groups (Scheme 41). [142a] 4-Methylene cyclohexanone was selectively con-verted into the E (wt-CHMO) or Z isomer (mutant-CHMO).…”

Organic Synthesis: Wherefrom and Whither? (Some Very Personal Reflections)

“…Hybrid catalysis has shown remarkable potential by amalgamating existing enzymes with non-natural cofactors, which when combined with directed evolution create new, highly efficient transformations. [58] Finally, if one accepts the proposition that truly revolutionary changes come primarily from serendipitous discoveries, then, recent demonstrations of multidimensional screening, [59] accelerated serendipity [60] and high-throughput discovery [61] of new types of reactions hold extraordinary potential for identifying fundamentally new types of reactivity. These activities must not cease, nor be marginalized by other sciences or more importantly policy makers and funding agencies.…”

P450 Monooxygenases Enable Rapid Late‐Stage Diversification of Natural Products via C−H Bond Activation

“…The increasing need for sustainability is changing the rules of synthetic chemistry considerably, driving the application of Green Chemistry principles, the current trend toward protecting‐group‐free syntheses and the continuous interest in the total synthesis of natural products in more elegant ways . This calls for the integration of enzymes into the synthetic toolbox, supported by the discovery of a broad diversity of novel enzymes (e. g. by metagenomics) and the recent success in tuning enzymes in vitro to process requirements by rational engineering and directed enzyme evolution . As a consequence, the term “Biocatalytic retrosynthesis” was introduced in 2013, which revitalised the attention given to the use of enzymes for upgrading synthetic routes to complex targets, implementing an effective tool to achieve FG installation in a highly selective fashion under mild reaction conditions …”