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3
Monooxygenase-Catalyzed Redox Cascade Biotransformations

Florian Rudroff and Marko D. Mihovilovic

3.1
Introduction

3.1.1
Scope of this Chapter
In this chapter, we present a historical overview on the development, investigation,
and application of oxygen-activating enzymes, focusing on monooxygenases, in
the context of cascade reactions. In the past decades, this enzyme class was
used very successfully in particular in the synthesis of valuable natural and
bioactive compounds. Starting from the very simple case of cofactor regeneration
by a complementary reductase, via the investigation of complex chemo-enzymatic
processes, to ultimately providing a future perspective with an artificial mini-
pathway composed of four consecutive redox reactions in a living organism, the
potential as well as the current limitations of monooxygenases will be outlined in
thefieldofappliedbiocatalysis.

3.1.2
Enzymatic Oxygenation

Specific and efficient insertion of oxygen originating from molecular oxygen into
an organic substrate is particularly intriguing because the direct oxyfunctionaliza-
tion of nonactivated compounds is still a challenge in synthetic chemistry. Several
oxidation processes based on molecular oxygen are developed by the industry to
transform alkanes, alkenes, and aromatic compounds into valuable oxygenated
intermediates such as alcohols, aldehydes, ketones, and carboxylic acids. Nonethe-
less, most of the applied catalytic systems are sophisticated and expensive, have
a limited substrate range, and often display a lack of regio- and stereoselectivity.
Over the past years, the need and demand for cleaner and more efficient oxidation
processes has become one of the major interests in chemical research. Biocatalysis
offers such an approach by the use of specialized oxidizing enzymes, namely
oxidases and mono- and dioxygenases.

Cascade Biocatalysis: Integrating Stereoselective and Environmentally Friendly Reactions, First Edition.
Edited by Sergio Riva and Wolf-Dieter Fessner.
c 2014 Wiley-VCH Verlag GmbH & Co. KGaA. Published 2014 by Wiley-VCH Verlag GmbH & Co. KGaA.