Biocatalytic Reductions and Chemical Versatility of the Old Yellow Enzyme Family of Flavoprotein Oxidoreductases

Abstract

The old yellow enzyme (OYE) family is a large group of flavin‐dependent redox biocatalysts with major applications in the industrial reduction of activated alkenes. These enzymes have broad specificity, are relatively stable, and have been made available in large quantities by using conventional genetic methods. The catalytic cycle comprises two half‐reactions: reduction of flavin mononucleotide by NAD(P)H followed by flavin oxidation through stereospecific reduction of the CC bond of a wide range of activated alkenes. Recent years have witnessed extensive investigation of these reactions, aided by knowledge of atomic resolution structures for selected family members. In turn, this has led to deep understanding of the stereochemical course of substrate reduction and expansion of the biocatalytic versatility of this enzyme family through engineering approaches. We provide an overview of the structures, mechanisms, and chemical specificity of the reactions catalyzed by the OYE members. We provide an overview of the biocatalytic potential of this family of enzymes and illustrate the value of combining mechanistic and structural studies of biocatalysts to guide future exploitation of these enzymes in industrial biocatalysis.

An enoate reductase Achr-OYE4 from Achromobacter sp. JA81: characterization and application in asymmetric bioreduction of C=C bonds

“…The result indicated that the source of reducing equivalents could affect the yield and enantiopurity of the product. Similar results were found for other OYEs, such as PETN and OPR3 (Toogood et al 2010).…”

“…Most characterized enoate reductases prefer NADPH over NADH as the cofactor (Chaparro-Riggers et al 2007;Toogood et al 2010), whereas only a few prefer NADH (Brige et al 2006;French and Bruce 1994), such as morphinone reductase, SYE1, and SYE3. In the present study, Achr-OYE4 displayed a preference for NADH on using all testing substrates, and the catalytic efficiency toward NADH Fig.…”

“…The asymmetric trans-hydrogenation function makes those enzymes important complementary tools for existing chemical catalysts (Brown et al 2002;Fox and Karplus 1994;Kohli and Massey 1998;Xu et al 1999). The substrate range reported covers conjugated enals, enones, ynones, nitroalkenes, α,β-unsaturated nitriles, β-nitro acrylates, and α,β-unsaturated carboxylic acids with high chemo-, regio-, and stereoselectivity, and the products often serve as versatile synthons in pharmaceutical and fine chemical industries (Bougioukou and Stewart 2008;Stueckler et al 2011;Stuermer et al 2007;Toogood et al 2010Toogood et al , 2012.…”

Asymmetric bioreduction of activated alkenes by a novel isolate of Achromobacter species producing enoate reductase

“…have been known for their abilities to biodegrade methyl tert-butyl ether (Eixarch and Constanti 2010), p-nitrophenol (Wan et al 2007), bisphenol (Zhang et al 2007), endosulfan (Li et al 2009), and hexavalent chromium (Zhu et al 2008) and to catalyze the asymmetric acyloin condensation reaction (Guo et al 2001) but not the reduction of alkenes. Bacteria from other genera such as Pseudomonas, Bacillus, Clostridium, Ruminococcus, Acetobacterium, Zymomonas, and Agrobacterium have been reported to contain enoate reductases (Toogood et al 2010). By mining the database, we found several protein sequences originated from the genome sequencing data of Achromobacter strains that are predicted to be OYE family members.…”

“…These enzymes are ubiquitous and widely distributed in biological sources including higher plants, bacteria, and lower fungi. In the last few decades, both whole cell preparations and isolated enoate reductases have been applied in chemical synthesis for asymmetric C0C reductions (Brenna et al 2012;Toogood et al 2010). The substrate spectrum of the OYE family as a whole covers a variety of activated alkenes and alkynes, such as conjugated enals, enones, and ynones, nitro-alkenes, α,β-unsaturated nitriles, β-nitro acrylates, and α,β-unsaturated carboxylic acids and their derivatives (Luo et al 2011;Stueckler et al 2011;Toogood et al 2010).…”