Enzymes dependent on nicotinamide cofactors are important components of the expanding range of asymmetric synthetic techniques. New challenges in asymmetric catalysis are arising in the field of deuterium labelling, where compounds bearing deuterium ( 2 H) atoms at chiral centres are becoming increasingly desirable targets for pharmaceutical and analytical chemists. However, utilisation of NADH-dependent enzymes for 2 H-labelling is not straightforward, owing to difficulties in supplying a suitably isotopically-labelled cofactor ([4-2 H]-NADH). Here we report on a strategy that combines a clean reductant (H 2 ) with a cheap source of 2 H-atoms ( 2 H 2 O) to generate and recycle [4-2 H]-NADH. By coupling [4-2 H]-NADH-recycling to an array of C=O, C=N, and C=C bond reductases, we demonstrate asymmetric deuteration across a range of organic molecules under ambient conditions with near-perfect chemo-, stereo-and isotopic selectivity. We demonstrate the synthetic utility of the system by applying it in the isolation of the heavy drug (1S,3'R)-[2',2',3'-2 H 3 ]solifenacin fumarate on a preparative scale.

No abstract

No abstract

has made ap rovisionalp atent application based on the discoveries demonstrated in this manuscript.Keywords: antiviral agents · nucleotide analogues · radical-SAM enzyme · tyrosyl radicals · viperin Figure 6. The proposed mechanism of catalysis by TtRSAD2. The 5'-dAdo radicalabstractst he Ha tom (red) at the C4' position of ribose to generate a C4'-centred radical intermediate. As ar esult of hyperconjugation between a po rbitalonC 4' and the s C3'ÀO3' orbital, assisted by ap rotein amino acid residue( AH), the 3'-OHg roupo ft he riboseforms awater molecule. The proton to generate the water molecule is provided by tyrosine either indirectly through ap roton hoppingp athway(1) or directly (2). Spontaneously, an electron from tyrosine reduces the substrate-radical intermediate. As a result, the nucleotide analogue product and ap rotein tyrosylradical are formed. The [4 FeÀ4S] 2 + clusteri sre-reduced and then,t he tyrosyl radicali s reducedbya ne lectron from the [4 FeÀ4S] + cluster.

Edited by Peter BrzezinskiViperin (RSAD2) is an antiviral radical S-adenosylmethionine (SAM) enzyme highly expressed in different cell types upon viral infection. Recently, it has been reported that the radical-SAM activity of viperin transforms cytidine triphosphate (CTP) to its analogue 3 0 -deoxy-3 0 ,4 0 -didehydro-CTP (ddhCTP). Based on biochemical studies and cell biological experiments, it was concluded that ddhCTP and its nucleoside form ddhC do not affect the cellular concentration of nucleotide triphosphates and that ddhCTP acts as replication chain terminator. However, our re-evaluation of the reported data and new results indicate that ddhCTP is not an effective viral chain terminator but depletes cellular nucleotide pools and interferes with mitochondrial activity to inhibit viral replication. Our analysis is consistent with a unifying view of the antiviral and radical-SAM activities of viperin.