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Abstract: Efficient H2 oxidation and production by hydrogenase enzymes has attracted much interest because of the possibilities it raises for clean energy cycling without the need for precious metal catalysts. Although hydrogenases are extremely active electrocatalysts, high surface-area electrode structures will be necessary if the enzymes are to find application in energy technologies. Taking inspiration from fuel cell electrode assemblies, in which metal nanoparticles are commonly mounted on particulate carbon supports encased in polymer electrolyte, we show that high surface-area hydrogenase electrodes can be constructed from enzyme-loaded pyrolytic graphite particles in pH-neutralised Nafion. Pyrolytic graphite is the favoured surface for direct electrochemistry of many redox proteins, and on sanding, yields micron-dimension platelike particles. By modifying graphite platelets with hydrogenase before assembling the particles into a network, we ensure a high, uniform enzyme coverage. Incorporation of hydrogenases into high surface-area conducting network electrodes enhanced electrocatalytic H2 oxidation currents by 30-times compared to values obtained for a planar hydrogenase electrode, while retaining efficient conductivity and H2 mass transport through the network. This approach should make it possible to directly compare enzyme and precious metal electrocatalysis and to benchmark what opportunities are possible with selective enzyme catalysts. [Copyright &y& Elsevier]

[Display omitted] Barriers to the ready adoption of biocatalysis into asymmetric synthesis for early stage medicinal chemistry are addressed, using ketone reduction by alcohol dehydrogenase as a model reaction. An efficient substrate screening approach is used to show the wide substrate scope of commercial alcohol dehydrogenase enzymes, with a high tolerance to chemical groups employed in drug discovery (heterocycle, trifluoromethyl and nitrile/nitro groups) observed. We use our screening data to build a preliminary predictive pharmacophore-based screening tool using Forge software, with a precision of 0.67/1, demonstrating the potential for developing substrate screening tools for commercially available enzymes without publicly available structures. We hope that this work will facilitate a culture shift towards adopting biocatalysis alongside traditional chemical catalytic methods in early stage drug discovery. [ABSTRACT FROM AUTHOR]