- Chemo-bio catalysis using carbon supports: application in H2-driven cofactor recycling
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Heterogeneous biocatalytic hydrogenation is an attractive strategy for clean, enantioselective CX reduction. This approach relies on enzymes powered by H2-driven NADH recycling. Commercially available carbon-supported metal (metal/C) catalysts are investigated here for direct H2-driven NAD+reduction. Selected metal/C catalysts are then used for H2oxidation with electrons transferredviathe conductive carbon support material to an adsorbed enzyme for NAD+reduction. These chemo-bio catalysts show improved activity and selectivity for generating bioactive NADH under ambient reaction conditions compared to metal/C catalysts. The metal/C catalysts and carbon support materials (all activated carbon or carbon black) are characterised to probe which properties potentially influence catalyst activity. The optimised chemo-bio catalysts are then used to supply NADH to an alcohol dehydrogenase for enantioselective (>99% ee) ketone reductions, leading to high cofactor turnover numbers and Pd and NAD+reductase activities of 441 h?1and 2347 h?1, respectively. This method demonstrates a new way of combining chemo- and biocatalysis on carbon supports, highlighted here for selective hydrogenation reactions.
- Cleary, Sarah E.,Grobert, Nicole,Reeve, Holly A.,Vincent, Kylie A.,Zhao, Xu,Zor, Ceren
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- A genetically encodable ligand for transfer hydrogenation
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Simple tripeptides are shown here to be versatile ligands for iridium-catalyzed transfer hydrogenations affording large acceleration effects. A water-soluble iridium complex with Gly-Gly-Phe, for example, catalyzes the reduction of diverse ketones, aldehydes, and imines by formate with turnover frequencies rivaling or outperforming those of established ligand systems. Regioselective reduction of coenzyme NAD+ to NADH illustrates the potential utility of this system for biotechnological applications. Because peptides are genetically encodable, they represent an attractive class of foldamer ligands for creating artificial metalloenzymes.
- Mayer, Clemens,Hilvert, Donald
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p. 3427 - 3431
(2013/07/19)
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