An Engineered Cholesterol Oxidase Catalyses Enantioselective Oxidation of Non‐steroidal Secondary Alcohols

Abstract

The enantioselective oxidation of 2°alcohols to ketones is an important reaction in synthetic chemistry, especially if it can be achieved using O 2 -driven alcohol oxidases under mild reaction conditions. However to date, oxidation of secondary alcohols using alcohol oxidases has focused on activated benzylic or allylic substrates, with unactivated secondary alcohols showing poor activity. Here we show that cholesterol oxidase (EC 1.1.3.6) could be engineered for activity towards a range of aliphatic, cyclic, acyclic, allylic and benzylic secondary alcohols. Additionally, since the variants demonstrated high (S)-selectivity, deracemisation reactions were performed in the presence of ammonia borane to obtain enantiopure (R)-alcohols.

Biocatalytic and Chemo-Enzymatic Synthesis of Quinolines and 2-Quinolones by Monoamine Oxidase (MAO-N) and Horseradish Peroxidase (HRP) Biocatalysts

“… 3 In fact, oxidases can catalyze a multitude of oxidative transformations at ambient temperature and pressure and, in some cases, without the need for any external cofactor additive or recycling system. For such reasons, oxidizing biocatalysts have been widely employed in the last decade in asymmetric reactions, 4 like the deracemization of chiral amines by monoamine oxidases (MAO-N) 5 or the enantioselective synthesis of alcohols by glucose oxidase (GOase M3–5) 6 or alcohol dehydrogenases (ADH). 7 Over the past few years, our group successfully demonstrated the possibility of employing oxidizing biocatalysts such as MAO-N and laccase also in the aromatization of aliphatic or partially saturated cyclic substrates into aromatic pyrroles, pyridines, indoles, and furans under mild reaction conditions.…”

Current Advances in the Enzyme Engineering of O2‐Dependent Enzymes – Boosting the Versatility and Applicability of Oxygenases and Oxidases

“…No variant could convert substrates with isopropyl residues on the cyclohexane backbone due to steric hindrances caused by FAD. [53] Similarly, the substrate preference of fungal aryl-alcohol oxidases (AAO) from Pleurotus eryngii was switched from primary alcohols to secondary alcohols. Computational simulations were used to select interesting amino acids subjected to SDM.…”

“…In addition, the variants were able to oxidise primary alcohols. No variant could convert substrates with isopropyl residues on the cyclohexane backbone due to steric hindrances caused by FAD [53] …”