Flavoprotein monooxygenases for oxidative biocatalysis: recombinant expression in microbial hosts and applications

Abstract

External flavoprotein monooxygenases comprise a group of flavin-dependent oxidoreductases that catalyze the insertion of one atom of molecular oxygen into an organic substrate and the second atom is reduced to water. These enzymes are involved in a great number of metabolic pathways both in prokaryotes and eukaryotes. Flavoprotein monooxygenases have attracted the attention of researchers for several decades and the advent of recombinant DNA technology caused a great progress in the field. These enzymes are subjected to detailed biochemical and structural characterization and some of them are also regarded as appealing oxidative biocatalysts for the production of fine chemicals and valuable intermediates toward active pharmaceutical ingredients due to their high chemo-, stereo-, and regioselectivity. Here, we review the most representative reactions catalyzed both in vivo and in vitro by prototype flavoprotein monooxygenases, highlighting the strategies employed to produce them recombinantly, to enhance the yield of soluble proteins, and to improve cofactor regeneration in order to obtain versatile biocatalysts. Although we describe the most outstanding features of flavoprotein monooxygenases, we mainly focus on enzymes that were cloned, expressed and used for biocatalysis during the last years.

Baeyer-Villiger oxidations: biotechnological approach

“…In general, they are divided in six subclasses (A-F) according to structural/sequence-based relations (van Berkel et al 2006). BVMOs are external monooxygenases containing noncovalently bound FAD or FMN and catalyze NAD(P)H dependent aerial oxygen insertions under the release of water (Balke et al 2012;Ceccoli et al 2014;Pazmino et al 2010a). Up to now, two different types of BVMOs are known.…”

The “Green” FMOs: Diversity, Functionality and Application of Plant Flavoproteins

“…The oxidation of these molecules, sometimes with high chemo-, regio-and enantio-selectivity, alters their physical and chemical properties, such as polarity, solubility, reactivity, and susceptibility for further enzymatic modifications [1]. Accordingly, FMOs are important oxidoreductases with large potential for development as biocatalysts within the biotechnological and pharmaceutical industries [1][2][3][4][5][6]. Traditionally, other oxygenase enzymes, such as cytochromes P450 (CYPs), have received comparatively more attention for their endogenous roles in vivo [7][8][9], and in regard to the identification and development of new enzyme reactions.…”

Photoenzymatic epoxidation of styrenes

“…For example, 2CDFMs catalyse regioselective aromatic hydroxylations and halogenation reactions as well as stereoselective epoxidation reactions. [1][2][3][4] For this, 2CDFMOs rely on the reductive activation of molecular oxygen mediated by an enzyme-bound, reduced flavin cofactor (generally the reduced form of flavin adenine dinucleotide, FADH 2 ). FADH 2 itself is regenerated by a NAD(P)H-dependent reductase.…”