Efficient Bio-Oxidations for the synthesis of natural or enantiopur compounds – NaturaDyRe

A large number of Baeyer-Villiger monooxygenase-like proteins has been identified in the protein data banks (UniProtKB) by sequence comparison. Bioinformatics analysis was used to select a limited number of proteins reflecting the diversity of this family. The corresponding genes were cloned and introduced into host microorganisms through High Throughput Cloning. The initially very low success due to the gene features (high rate of GC nucleic acids) was improved by the development of specific protocols. High and medium throughput screening assays were developed and carried out to determine the activity profiles and the enantioselectivity of these enzymes. Correlations between sequences, structural models of biocatalytic enzymes and their properties were investigated.
The productivity of some reactions has been improved by Dynamic Kinetic Resolution. These methods allow to exceed the 50% maximum efficiency inherent in conventional kinetic resolution by combining simultaneously in situ substrate racemisation and microbiological reaction.

A hundred of new Baeyer-Villiger monooxygenases was discovered. Two of them displayed an original reactivity towards a, ß-unsaturated ketones, an original route to difficult- to-access chiral ene- and enol-lactones. Peculiar biocatalysts were built in order to eliminate undesirable side reactions, others were built for the synthesis of aromatic molecules via enzymatic cascade reactions.

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This work resulted in two publications in international journals (Chemical Communications, Biochemistry), twelve oral presentations or posters in national or international conferences. Two PhD theses were defended.

This project is aimed to providing a new tool to chemists in laboratory or industrial production: a highly efficient regio- and / or enantioselective biocatalysed Baeyer-Villiger oxidation in high concentration.

In a first step, a set of new enzymes displaying complementary activities will be proposed to face up to the weakness of the current offer of Baeyer-Villigerases (a dozen available enzymes in laboratory and only one commercialised). The genes of putative BVases will be identified in genomic data banks by comparison of sequences then introduced into host microorganism via a high throughput cloning. High and medium throughput screenings intended to report respectively the activity and enantioselectivity profiles of these enzymes will be set up and carried out in order to develop a tool for making easier and faster the choice of the catalyst

On the other hand, productivity often reaches limits because of inhibition (or toxicity) phenomena. To move closer to industrial benchmarks, a process based on adsorbent resins will be implemented to increase concentrations.

Besides their "green" and sustainable aspect, Baeyer-Villiger biooxidations present an enzymatic version more efficient in terms of enantioselectivity than the chemical version. In order to harness these features, Dynamic Kinetic Resolution (DKR) process associating in situ substrate racemisation simultaneously with microbiological Baeyer-Villiger oxidation (to overcome the maximal 50 % of yield inherent to classic resolutions) will be developed. Various chemical and enzymatic racemisation conditions will be investigated. DKR and resin-based process will be finally brought together in a Dynamic Kinetic Resolution process at High Concentration, which should lead to a significant increase in productivity.

The approach proposed in this project will be validated by the industrial scale production of molecules of interest in the field of flavours or synthesis intermediates.