Artificial Multi-Enzyme Networks for the Asymmetric Amination of sec-Alcohols

Various artificial network designs that involve biocatalysts were tested for the asymmetric amination of sec-alcohols to the corresponding α-chiral primary amines. The artificial systems tested involved three to five redox enzymes and were exemplary of a range of different sec-alcohol substrates. Alcohols were oxidised to the corresponding ketone by an alcohol dehydrogenase. The ketones were subsequently aminated by employing a ω-transaminase. Of special interest were redox-neutral designs in which the hydride abstracted in the oxidation step was reused in the amination step of the cascade. Under optimised conditions up to 91 % conversion of an alcohol to the amine was achieved. Trickle-down effect: The asymmetric amination of sec-alcohols to the corresponding α-chiral primary amines was performed with a biocatalytic cascade whereby the various steps were interconnected through the cofactors/cosubstrates. In a redox-neutral cascade and under optimised conditions, up to 91 % conversion of an alcohol to the amine was achieved.