Nonnatural Reactivity of Cofactor-Dependent Enzymes upon Light Irradiation

Key words

ketoreductase - photoexcitation - nicotinamide-dependent enzymes - debromination - lactones

Significance

An asymmetric light-mediated reductive debromination of racemic α-bromolactones is reported by the Hyster group. The combination of a ketoreductase derived from either Lactobacillus kefiri (LKADH) or Ralstonia (RasADH), NADP⁺, and blue LED light furnished the desired lactones in high yields (≤91%) and good to excellent enantioselectivities (er ≤ 98:2).

Comment

A great challenge in biocatalysis is the discovery and development of novel reaction pathways and catalytic functions. The authors demonstrate that a nicotinamide-dependent keto­reductase can change its natural function from carbonyl reduction to that of a radical initiator and chiral source of hydrogen, simply by irradiation of the cofactor with light. This strategy leads to novel and selective radical-mediated reactions.