Biocatalysis is an increasingly common feature of the modern synthetic organic toolbox, providing access to highly selective reactivity under benign conditions. Notably, the fine chemicals sector employs oxidoreductases as catalysts in the reduction of C=O, C=N, and C=C functionalities. Such transformations occur by enzymatic transfer of a hydride moiety from a biological cofactor (NADH), yielding the product and an oxidised NAD+ unit. Recycling of the NADH is essential to sustain a cost-effective industrial process, with the addition of excess sacrificial compounds (such as glucose or formate) often being required to re-reduce the NAD+. This presentation will describe an alternative strategy for cofactor recycling, driven purely by a supply of H2 gas at ambient pressure and temperature. This method, termed “HydRegen”, utilises a H2-oxidation catalyst (hydrogenase) to supply electrons, via an electronically conducting carbon support, to a co-immobilised NAD+ reductase, which in turn regenerates NADH from NAD+. This modular system can drive a wide range of NADH-dependent bio-hydrogenations (including converting ketones to chiral alcohols), and allows for facile recovery of the enzymes afterwards. Recent work to develop the catalyst for use in isotopic labelling experiments will also be discussed, demonstrating the ability of the system to function without the requirement for expensive pre-labelled deuterated pre-cursors. Hence, this presentation will provide an overview of a novel solution to the cofactor recycling problem, one that gives rise to cleaner and more-efficient biocatalysis.

Cleaning up biocatalysis: A modular heterogeneous platform for H2-driven enzymatic reactions

256th National Meeting (2018)

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